ORCID Profile
0000-0002-9560-8400
Current Organisation
Australian National University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Nanotechnology | Materials Engineering Not Elsewhere Classified | Nanotechnology | Materials Engineering | Condensed Matter Physics—Structural Properties | Nanoscale Characterisation | Materials Engineering not elsewhere classified | Elemental Semiconductors | Nanomaterials | Surfaces and Structural Properties of Condensed Matter | Condensed Matter Physics | Functional Materials | Other Electronic Engineering | Condensed Matter Physics—Electronic And Magnetic Properties; | Optics And Opto-Electronic Physics | Structural properties of condensed matter | Condensed matter physics | Optical Physics | Memory Structures | Functional materials | Computer Hardware | Microtechnology | Photonics, Optoelectronics and Optical Communications | Theory and design of materials | Electrical and Electronic Engineering | Nanophotonics | Petrophysics | Interdisciplinary Engineering Not Elsewhere Classified | Condensed Matter Modelling and Density Functional Theory | Condensed Matter Characterisation Technique Development | Nanofabrication, Growth and Self Assembly
ANZSRC Socio-Economic Objective (SEO)
Physical sciences | Expanding Knowledge in the Physical Sciences | Other | Integrated circuits and devices | Ceramics, Glass and Industrial Mineral Products not elsewhere classified | Computer hardware and electronic equipment not elsewhere classified | Ceramics | Expanding Knowledge in Technology | Expanding Knowledge in Engineering | Other | Solar-photoelectric | Network transmission equipment | Earth sciences | Chemical sciences | Integrated Circuits and Devices | Expanding Knowledge in the Medical and Health Sciences | Scientific instrumentation | Industrial Instruments | Expanding Knowledge in the Chemical Sciences | Scientific Instruments | Expanding Knowledge in the Biological Sciences | Communication equipment not elsewhere classified |
Related Links
Publications
Structural characterization of B-doped diamond nanoindentation tips
Publisher: Springer Science and Business Media LLC
Date: 24-11-2011
DOI: 10.1557/JMR.2011.377
Seenomaly: Vision-based linting of gui animation effects against design-don't guidelines
Publisher: ACM
Date: 27-06-2020
Controlled formation of metastable germanium polymorphs
Publisher: American Physical Society (APS)
Date: 25-04-2014
Can Software Engineering Harness the Benefits of Advanced AI?
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2022
The Compelling Case for Indentation as a Functional Exploratory and Characterization Tool
Publisher: Wiley
Date: 30-07-2015
DOI: 10.1111/JACE.13729
Medium-range order in amorphous silicon investigated by constrained structural relaxation of two-body and four-body electron diffraction data
Publisher: Elsevier BV
Date: 2012
A Unified Business-Driven Cloud Management Framework
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2016
Design Pattern as a Service for Blockchain-Based Self-Sovereign Identity
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2020
FLRA: A Reference Architecture for Federated Learning Systems
Publisher: Springer International Publishing
Date: 2021
Nanoindentation-induced deformation of Ge
Publisher: AIP Publishing
Date: 10-04-2002
DOI: 10.1063/1.1469660
Abstract: The deformation mechanisms of crystalline (100) Ge were studied using nanoindentation, cross sectional transmission electron microscopy (XTEM) and Raman microspectroscopy. For a wide range of indentation conditions using both spherical and pointed indenters, multiple discontinuities were found in the force–displacement curves on loading, but no discontinuities were found on unloading. Raman microspectroscopy, measured from s les which had plastically deformed on loading, showed a spectrum shift from that in pristine Ge, suggesting only residual strain. No evidence (such as extra Raman bands) was found to suggest that any pressure-induced phase transformations had occurred, despite the fact that the material had undergone severe plastic deformation. Selected area diffraction pattern studies of the mechanically damaged regions also confirmed the absence of additional phases. Moreover, XTEM showed that, at low loads, plastic deformation occurs by twinning and dislocation motion. This indicates that the hardness of Ge measured by indentation is not primarily dominated by phase transformation, rather by the nucleation and propagation of twin bands and/or dislocations.
New insight into pressure-induced phase transitions of amorphous silicon: the role of impurities
Publisher: International Union of Crystallography (IUCr)
Date: 15-05-2013
DOI: 10.1107/S0021889813010509
Abstract: The pressure-induced phase transformations of a form of amorphous silicon (a-Si) with well characterized impurity levels and structure are examined at pressures up to 40 GPa using in situ synchrotron X-ray radiation. At ∼12 GPa crystallization commences, but it is not completed until ∼16 GPa. At higher pressures, not all the crystalline phases observed for crystalline silicon (c-Si) appear. On pressure release, none of the metastable crystalline phases observed for c-Si nucleate. Instead an amorphous phase is re-formed. This is in contrast to all previous diamond-anvil studies on a-Si. If full pressure-induced crystallization occurred, the material remained crystalline on unloading. The formation of a-Si upon unloading was only observed when a high-density amorphous phase was reported on loading. The fully characterized nature of the a-Si used in this current study allows for the interpretation of this significant ersity in terms of impurity content of the a-Si used. Namely, this suggests that `ideal' (pure, voidless, structurally relaxed) a-Si will follow the same transition pathway as observed for c-Si, while crystallization of a-Si forms with a high impurity content is retarded or even inhibited. The a-Si used here straddles both regimes and thus, although full crystallization occurs, the more complex crystalline structures fail to nucleate.
A Pattern Collection for Blockchain-based Applications
Publisher: ACM
Date: 04-07-2018
Effects of carbon on ion-implantation-induced disorder in GaN
Publisher: AIP Publishing
Date: 24-12-2007
DOI: 10.1063/1.2827587
Abstract: Wurtzite GaN films bombarded with 40keV C ions to high doses (5×1017 and 1×1018cm−2) are studied by a combination of Rutherford backscattering/channeling spectrometry, transmission electron microscopy, and soft x-ray absorption spectroscopy. Results show that, contrary to other ion species, implanted C forms nitrilelike carbon-nitride bonds (CN) and suppresses ion-beam-induced material decomposition involving the formation and agglomeration of ≳5-nm-large N2 gas bubbles.
Cold nanoindentation of germanium
Publisher: AIP Publishing
Date: 10-07-2017
DOI: 10.1063/1.4993163
Nanoindentation of Ion Implanted and Deposited Amorphous Silicon
Publisher: Springer Science and Business Media LLC
Date: 2005
DOI: 10.1557/PROC-841-R10.3/T6.3
Abstract: The deformation behavior of both ion-implanted and deposited amorphous Si (a-Si) films has been studied using spherical nanoindentation, followed by analysis using Raman spectroscopy and cross-sectional transmission electron microscopy (XTEM). Indentation was carried out on both unannealed a-Si films (the so-called unrelaxed state) and in ion implanted films that were annealed to 450°C to fully relax the amorphous film. The dominant mode of deformation in unrelaxed films was via plastic flow of the amorphous phase rather than phase transformation, with measured hardness being typically 75–85% of that of crystalline Si. In contrast, deformation via phase transformation was clearly observed in the relaxed state of ion implanted a-Si, with the load-unload curves displaying characteristic discontinuities and Raman and XTEM indicating the presence of high-pressure crystalline phases Si-III and Si-XII following pressure release. In such cases the measured hardness was within 5% of that of the crystalline phase.
Synthesis of Novel Phases in Si Nanowires Using Diamond Anvil Cells at High Pressures and Temperatures
Publisher: American Chemical Society (ACS)
Date: 27-01-2021
Nitrogen-rich indium nitride
Publisher: AIP Publishing
Date: 25-05-2004
DOI: 10.1063/1.1711173
Abstract: Elastic recoil detection analysis, using an incident beam of 200 MeV Au ions, has been used to measure indium nitride films grown by radio-frequency sputtering. It is shown that the films have nitrogen-rich stoichiometry. Nitrogen vacancies are therefore unlikely to be responsible for the commonly observed high background carrier concentration. Ultraviolet Raman and secondary ion mass spectroscopy measurements are used to probe the state of the excess nitrogen. The nitrogen on indium anti-site defect is implicated, though other possibilities for the site of the excess nitrogen, such as molecular nitrogen, or di-nitrogen interstitials cannot be excluded. It is further shown that a shift in the (0002) x-ray diffraction peak correlates with the excess nitrogen, but not with the oxygen observed in some s les.
Towards Effective Data Augmentations via Unbiased GAN Utilization
Publisher: No publisher found
Date: 2019
Wireframe-based UI Design Search through Image Autoencoder
Publisher: Association for Computing Machinery (ACM)
Date: 16-06-2020
DOI: 10.1145/3391613
Abstract: UI design is an integral part of software development. For many developers who do not have much UI design experience, exposing them to a large database of real-application UI designs can help them quickly build up a realistic understanding of the design space for a software feature and get design inspirations from existing applications. However, existing keyword-based, image-similarity-based, and component-matching-based methods cannot reliably find relevant high-fidelity UI designs in a large database alike to the UI wireframe that the developers sketch, in face of the great variations in UI designs. In this article, we propose a deep-learning-based UI design search engine to fill in the gap. The key innovation of our search engine is to train a wireframe image autoencoder using a large database of real-application UI designs, without the need for labeling relevant UI designs. We implement our approach for Android UI design search, and conduct extensive experiments with artificially created relevant UI designs and human evaluation of UI design search results. Our experiments confirm the superior performance of our search engine over existing image-similarity or component-matching-based methods and demonstrate the usefulness of our search engine in real-world UI design tasks.
Is It Time to Rethink Syphilis Control?
Publisher: Oxford University Press (OUP)
Date: 16-10-2015
DOI: 10.1093/CID/CIU813
Phase stability of silicon during indentation at elevated temperature: evidence for a direct transformation from metallic Si-II to diamond cubic Si-I
Publisher: Springer Science and Business Media LLC
Date: 03-2012
DOI: 10.1557/MRC.2011.24
A compliance checking framework for DNN models
Publisher: International Joint Conferences on Artificial Intelligence Organization
Date: 08-2019
Abstract: Growing awareness towards ethical use of machine learning (ML) models has created a surge for the development of fair models. Existing work in this regard assumes the presence of sensitive attributes in the data and hence can build classifiers whose decisions remain agnostic to such attributes. However, in the real world settings, the end-user of the ML model is unaware of the training data besides, building custom models is not always feasible. Moreover, utilizing a pre-trained model with high accuracy on certain dataset can not be assumed to be fair. Unknown biases in the training data are the true culprit for unfair models (i.e., disparate performance for groups in the dataset). In this preliminary research, we propose a different lens for building fair models by enabling the user with tools to discover blind spots and biases in a pre-trained model and augment them with corrective measures.
Correlation of indentation-induced phase transformations with the degree of relaxation of ion-implanted amorphous silicon
Publisher: Springer Science and Business Media LLC
Date: 26-03-2013
DOI: 10.1557/JMR.2013.32
Towards Effective Data Augmentations via Unbiased GAN Utilization
Publisher: Springer International Publishing
Date: 2019
Blockchain-based federated learning for device failure detection in industrial iot
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2021
Stratosphere: Dynamic IP Overlay Above the Clouds
Publisher: IEEE
Date: 10-2017
DOI: 10.1109/LCN.2017.75
Continuous Integration, Delivery and Deployment: A Systematic Review on Approaches, Tools, Challenges and Practices
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2017
Data Service API Design for Data Analytics
Publisher: Springer International Publishing
Date: 2018
Design and Implementation of Monitoring System for Extracurricular Physical Exercise Based on Energy Consumption Measurement
Publisher: Fuji Technology Press Ltd.
Date: 20-01-2019
DOI: 10.20965/JACIII.2019.P0146
Abstract: Although the present attendance management system, adopted by universities, determines students’ physical presence. It does not determine whether they perform physical activities. It is important to monitor students’ extracurricular physical exercise scientifically and effectively to solve the actual effect of extracurricular physical exercise attendance and exercise. Calorie management is one solution to this problem. Additionally, an extracurricular physical exercise monitoring and management system is developed to record the energy consumption of students during their physical activities. To realize the demand for the management of calories and the monitoring and analysis of the energy consumption of students through the two development of the energy consumption instrument. This plan has certain significance for solving the actual effect of extracurricular physical training.
ARA-Assessor: Application-Aware Runtime Risk Assessment for Cloud-Based Business Continuity
Publisher: Springer International Publishing
Date: 2017
Adopting continuous delivery and deployment: Impacts on team structures, collaboration and responsibilities
Publisher: ACM
Date: 15-06-2017
Nanomechanical properties of sputter-deposited HfO2 and HfxSi1-xO2 thin films
Publisher: AIP Publishing
Date: 15-08-2011
DOI: 10.1063/1.3627155
Abstract: The mechanical properties of sputter-deposited HfO2 and HfxSi1-xO2 films were studied as a function of composition using nanoindentation. The elastic modulus and hardness were measured at room temperature for as-deposited films of varying Hf content and for films subjected to annealing at 1000 °C. The elastic modulus and hardness of as-deposited films were found to increase monotonically with increasing HfO2 content, with the hardness increasing from 5.0 ± 0.3 GPa for pure SiO2 to 8.4 ± 0.4 GPa for pure HfO2. All films were found to be harder after annealing at 1000 °C, with the increase for SiO2 films attributed to densification of the SiO2 network and that for the HfxSi1-xO2 films to a combination of phase separation, densification, and crystallization.
Adversarial Examples for Graph Data: Deep Insights into Attack and Defense
Publisher: International Joint Conferences on Artificial Intelligence Organization
Date: 08-2019
Abstract: Graph deep learning models, such as graph convolutional networks (GCN) achieve state-of-the-art performance for tasks on graph data. However, similar to other deep learning models, graph deep learning models are susceptible to adversarial attacks. However, compared with non-graph data the discrete nature of the graph connections and features provide unique challenges and opportunities for adversarial attacks and defenses. In this paper, we propose techniques for both an adversarial attack and a defense against adversarial attacks. Firstly, we show that the problem of discrete graph connections and the discrete features of common datasets can be handled by using the integrated gradient technique that accurately determines the effect of changing selected features or edges while still benefiting from parallel computations. In addition, we show that an adversarially manipulated graph using a targeted attack statistically differs from un-manipulated graphs. Based on this observation, we propose a defense approach which can detect and recover a potential adversarial perturbation. Our experiments on a number of datasets show the effectiveness of the proposed techniques.
Annealing kinetics of nanoindentation-induced polycrystalline high pressure phases in crystalline silicon
Publisher: AIP Publishing
Date: 26-03-2007
DOI: 10.1063/1.2716854
Abstract: Transformation kinetics of nanoindented zones in silicon containing high pressure crystalline phases (Si III and Si XII) during annealing (100°C& T& °C) have been studied using Raman microspectroscopy and cross-sectional transmission electron microscopy. Signature peaks associated with Si III/XII in the Raman spectra were monitored to track the annealing of these phases to polycrystalline Si I as a function of annealing time and temperature. An overall activation energy for this transformation was found to be 0.67eV. During annealing, Si XII disappeared faster than Si III, suggesting either that Si XII first converts to Si III or that Si XII transforms to polycrystalline Si I faster than Si III.
Crystal structure of laser-induced subsurface modifications in Si
Publisher: Springer Science and Business Media LLC
Date: 04-06-2015
Hybrid Networks: Improving Deep Learning Networks via Integrating Two Views of Images
Publisher: No publisher found
Date: 2018
The Blockchain as a Software Connector
Publisher: IEEE
Date: 04-2016
StageFS: A Parallel File System Optimizing Metadata Performance for SSD Based Clusters
Publisher: IEEE
Date: 08-2016
Continuous validation for data analytics systems
Publisher: ACM
Date: 14-05-2016
Engineering complex data integration, harmonization and visualization systems
Publisher: Elsevier BV
Date: 12-2019
Blockchains for Business Process Management - Challenges and Opportunities
Publisher: Association for Computing Machinery (ACM)
Date: 26-02-2018
DOI: 10.1145/3183367
Abstract: Blockchain technology offers a sizable promise to rethink the way interorganizational business processes are managed because of its potential to realize execution without a central party serving as a single point of trust (and failure). To stimulate research on this promise and the limits thereof, in this article, we outline the challenges and opportunities of blockchain for business process management (BPM). We first reflect how blockchains could be used in the context of the established BPM lifecycle and second how they might become relevant beyond. We conclude our discourse with a summary of seven research directions for investigating the application of blockchain technology in the context of BPM.
Mechanical deformation of InP and GaAs by spherical indentation
Publisher: AIP Publishing
Date: 21-05-2001
DOI: 10.1063/1.1372207
Abstract: The mechanical deformation by spherical indentation of both crystalline InP and GaAs was characterized using cross-sectional transmission electron microscopy (XTEM) and atomic force microscopy. All load–unload curves show a discontinuity (or “pop in”) during loading. Slip bands oriented along {111} planes are visible in XTEM micrographs from residual indentations in both materials and no evidence of any phase transformations was found. Higher load indentations (35 mN for InP and 50 mN for GaAs) also revealed subsurface cracking. In contrast no cracking was found beneath a 25 mN InP indent although the hardness and modulus data are almost identical to those of the cracked s le. The subsurface cracks are thought to be nucleated by high stress concentrations caused by dislocation pileup.
Phase Transformation Dependence on Initial Plastic Deformation Mode in Si via Nanoindentation
Publisher: Springer Science and Business Media LLC
Date: 30-09-2016
Nanocrystalline hexagonal diamond formed from glassy carbon
Publisher: Springer Science and Business Media LLC
Date: 29-11-2016
DOI: 10.1038/SREP37232
Abstract: Carbon exhibits a large number of allotropes and its phase behaviour is still subject to significant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defined material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100 GPa and 400 °C. The nanocrystalline material was recovered at ambient and analysed using diffraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic flow under compression in the diamond anvil cell, which lowers the energy barrier by “locking in” favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by first principles calculations of transformation pathways and explains why the new phase is found in an annular region. Our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.
Formation of ordered arrays of gold particles by nanoindentation templating
Publisher: Wiley
Date: 22-10-2013
Analysis of Blockchain Solutions for IoT: A Systematic Literature Review
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2019
Visual–Tactile Perception of Biobased Composites
Publisher: MDPI AG
Date: 23-02-2023
DOI: 10.3390/MA16051844
Abstract: Biobased composites offer unique properties in the context of sustainable material production as well as end-of-life disposal, which places them as viable alternatives to fossil-fuel-based materials. However, the large-scale application of these materials in product design is hindered by their perceptual handicaps and understanding the mechanism of biobased composite perception, and its constituents could pave the way to creating commercially successful biobased composites. This study examines the role of bimodal (visual and tactile) sensory evaluation in the formation of biobased composite perception through the Semantic Differential method. It is observed that the biobased composites could be grouped into different clusters based on the dominance and interplay of various senses in perception forming. Attributes such as Natural, Beautiful, and Valuable are seen to correlate with each other positively and are influenced by both visual and tactile characteristics of the biobased composites. Attributes such as Complex, Interesting, and Unusual are also positively correlated but dominated by visual stimuli. The perceptual relationships and components of beauty, naturality, and value and their constituent attributes are identified, along with the visual and tactile characteristics that influence these assessments. Material design leveraging these biobased composite characteristics could lead to the creation of sustainable materials that would be more attractive to designers and consumers.
Contrastive Counterfactual Learning for Causality-aware Interpretable Recommender Systems
Publisher: ACM
Date: 21-10-2023
Evidence for the R8 phase of germanium
Publisher: American Physical Society (APS)
Date: 20-02-2013
Phase transformations induced by spherical indentation in ion-implanted amorphous silicon
Publisher: AIP Publishing
Date: 07-2006
DOI: 10.1063/1.2210767
Abstract: The deformation behavior of ion-implanted (unrelaxed) and annealed ion-implanted (relaxed) amorphous silicon (a-Si) under spherical indentation at room temperature has been investigated. It has been found that the mode of deformation depends critically on both the preparation of the amorphous film and the scale of the mechanical deformation. Ex situ measurements, such as Raman microspectroscopy and cross-sectional transmission electron microscopy, as well as in situ electrical measurements reveal the occurrence of phase transformations in all relaxed a-Si films. The preferred deformation mode of unrelaxed a-Si is plastic flow, only under certain high load conditions can this state of a-Si be forced to transform. In situ electrical measurements have revealed more detail of the transformation process during both loading and unloading. We have used ELASTICA simulations to obtain estimates of the depth of the metallic phase as a function of load, and good agreement is found with the experiment. On unloading, a clear change in electrical conductivity is observed to correlate with a “pop-out” event on load versus penetration curves.
New and Emerging Ideas Track 2018
Publisher: IEEE
Date: 04-2018
Structural characterization of pressure-induced amorphous silicon
Publisher: American Physical Society (APS)
Date: 23-04-2009
Transmission electron microscopy observation of deformation microstructure under spherical indentation in silicon
Publisher: AIP Publishing
Date: 04-12-2000
DOI: 10.1063/1.1332110
Abstract: Spherical indentation of crystalline silicon has been studied using cross-sectional transmission electron microscopy (XTEM). Indentation loads were chosen below and above the yield point for silicon to investigate the modes of plastic deformation. Slip planes are visible in the XTEM micrographs in both indentation loads studied. A thin layer of polycrystalline material has been identified (indexed as Si-XII from diffraction patterns) on the low-load indentation. The higher-load indentation revealed a large region of amorphous silicon. The sequence of structural deformation by indentation in silicon has been observed with the initial deformation mechanism being slip until phase transformations can take place.
Message from IEEE TrustCom 2019 General Chairs
Publisher: IEEE
Date: 08-2019
Non-Intrusive Anomaly Detection With Streaming Performance Metrics and Logs for DevOps in Public Clouds: A Case Study in AWS
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2016
The influence of hold time on the onset of plastic deformation in silicon
Publisher: AIP Publishing
Date: 24-12-2015
DOI: 10.1063/1.4938480
Abstract: The transformation of diamond-cubic silicon to the metallic β-Sn phase is known to be “sluggish,” even when the critical pressure (∼11 GPa) for the transformation is reached. In this letter, we use nanoindentation to apply pressures to just above the critical threshold. In this regime, the s le displays purely elastic behavior at zero hold time. As the hold time at maximum load is increased up to 180 s, the percentage of indents that plastically deform also increase. Interestingly, the indents deform via one of two distinct processes: either via a phase transformation to a mixed bc8/r8-Si end phase, or by initiation of crystalline defects. Raman spectroscopy and cross-sectional transmission electron microscopy are used to show that the two deformation mechanisms are mutually exclusive under the indentation conditions presented here, and elastic modelling was utilized to propose a model for this mutually exclusive behavior. Hence, this behavior enhances the potential for application of the exotic bc8/r8-Si end phase.
Temperature-dependent mechanical deformation of silicon at the nanoscale: Phase transformation versus defect propagation
Publisher: AIP Publishing
Date: 28-02-2015
DOI: 10.1063/1.4921534
Abstract: This study uses high-temperature nanoindentation coupled with in situ electrical measurements to investigate the temperature dependence (25–200 °C) of the phase transformation behavior of diamond cubic (dc) silicon at the nanoscale. Along with in situ indentation and electrical data, ex situ characterizations, such as Raman and cross-sectional transmission electron microscopy, have been used to reveal the indentation-induced deformation mechanisms. We find that phase transformation and defect propagation within the crystal lattice are not mutually exclusive deformation processes at elevated temperature. Both can occur at temperatures up to 150 °C but to different extents, depending on the temperature and loading conditions. For nanoindentation, we observe that phase transformation is dominant below 100 °C but that deformation by twinning along {111} planes dominates at 150 °C and 200 °C. This work, therefore, provides clear insight into the temperature dependent deformation mechanisms in dc-Si at the nanoscale and helps to clarify previous inconsistencies in the literature.
HDM-MC in-Action: A Framework for Big Data Analytics across Multiple Clusters
Publisher: IEEE
Date: 07-2018
Quantifying the plant actin cytoskeleton response to applied pressure using nanoindentation
Publisher: Springer Science and Business Media LLC
Date: 14-05-2017
DOI: 10.1007/S00709-016-0984-9
Abstract: Detection of potentially pathogenic microbes through recognition by plants and animals of both physical and chemical signals associated with the pathogens is vital for host well-being. Signal perception leads to the induction of a variety of responses that augment pre-existing, constitutive defences. The plant cell wall is a highly effective preformed barrier which becomes locally reinforced at the infection site through delivery of new wall material by the actin cytoskeleton. Although mechanical stimulation can produce a reaction, there is little understanding of the nature of physical factors capable of triggering plant defence. Neither the magnitude of forces nor the contact time required has been quantified. In the study reported here, mechanical stimulation with a tungsten microneedle has been used to quantify the response of Arabidopsis plants expressing an actin-binding protein tagged with green fluorescent protein (GFP) to reveal the organisation of the actin cytoskeleton. Using confocal microscopy, the response time for actin reorganisation in epidermal cells of Arabidopsis hypocotyls was shown to be 116 ± 49 s. Using nanoindentation and a diamond spherical tip indenter, the magnitude of the forces capable of triggering an actin response has been quantified. We show that Arabidopsis hypocotyl cells can detect a force as small as 4 μN applied for as short a time as 21.6 s to trigger reorganisation of the actin cytoskeleton. This force is an order of magnitude less than the potential invasive force determined for a range of fungal and oomycete plant pathogens. To our knowledge, this is the first quantification of the magnitude and duration of mechanical forces capable of stimulating a structural defence response in a plant cell.
The effect of deposition energy on the microstructure and mechanical properties of high speed steel films prepared using a filtered cathodic vacuum arc
Publisher: Elsevier BV
Date: 08-2010
Identification of nanoindentation-induced phase changes in silicon by in situ electrical characterization
Publisher: AIP Publishing
Date: 15-04-2007
DOI: 10.1063/1.2724803
Abstract: In situ electrical measurements during nanoindentation of Czochralski grown p-type crystalline silicon (100) have been performed using a conducting diamond Berkovich indenter tip. Through-tip current monitoring with a sensitivity of ∼10pA and extraction of current-voltage curves at various points on the complete load-unload cycle have been used to track the phase transformations of silicon during the loading and unloading cycle. Postindent current-voltage curves prove to be extremely sensitive to phase changes during indentation, as well as to the final phase composition within the indented volume. For ex le, differences in the final structure are detected by current-voltage measurements even in an unloading regime in which only amorphous silicon is expected to form. The electrical measurements are interpreted with the aid of previously reported transmission electron microscopy and Raman microspectroscopy measurements.
Constructing a System Knowledge Graph of User Tasks and Failures from Bug Reports to Support Soap Opera Testing
Publisher: ACM
Date: 10-10-2022
Rate-dependent phase transformations in nanoindented germanium
Publisher: AIP Publishing
Date: 15-06-2009
DOI: 10.1063/1.3151967
Abstract: There is considerable controversy over the deformation behavior of germanium (Ge) under nanoindentation using a sharp diamond tip, with a erse range of observations that suggest competing mechanisms. Here we show the deformation mechanism of Ge can be controlled by the rate of applied load. Loading rate is varied over three orders of magnitude using depth-sensing nanoindentation. At slow loading rates, shear-induced plasticity is observed. At rapid loading rates (& mN s−1), pressure-induced phase transformations are detected by ex situ micro-Raman spectroscopy and transmission electron microscopy. This switch in the deformation mechanism is due to the differing rate sensitivities of the respective deformation modes, shear-induced plasticity or pressure-induced phase transformation.
Mechanical deformation of single-crystal ZnO
Publisher: AIP Publishing
Date: 11-02-2002
DOI: 10.1063/1.1448175
Abstract: The deformation behavior of bulk ZnO single crystals is studied by a combination of spherical nanoindentation and atomic force microscopy. Results show that ZnO exhibits plastic deformation for relatively low loads (≳4–13 mN with an ∼4.2 μm radius spherical indenter). Interestingly, the elastic–plastic deformation transition threshold depends on the loading rate, with faster loading resulting, on average, in larger threshold values. Multiple discontinuities (so called “pop-in” events) in force–displacement curves are observed during indentation loading. No discontinuities are observed on unloading. Slip is identified as the major mode of plastic deformation in ZnO, and pop-in events are attributed to the initiation of slip. An analysis of partial load–unload data reveals values of the hardness and Young’s modulus of 5.0±0.1 and 111.2±4.7 GPa, respectively, for a plastic penetration depth of 300 nm. Physical processes determining deformation behavior of ZnO are discussed.
Observation of enhanced defect emission and excitonic quenching from spherically indented ZnO
Publisher: AIP Publishing
Date: 21-08-2006
DOI: 10.1063/1.2338552
Abstract: The influence of spherical nanoindentation on the band edge and deep level emission of single crystal c-axis ZnO has been studied by cathodoluminescence (CL) spectroscopy and monochromatic imaging. Excitonic emission is quenched at the indent site and defect emission in the range of 450–720nm is enhanced. Analysis of CL monochromatic images and spectra suggests that at least two different defect states are responsible for the broad defect emission band. Additionally, the indents result in a strong crystallographic dependence of the defect emission, producing a rosette feature with [112¯0] [21¯1¯0], and [12¯10] orientations that reflect the star-shaped luminescence quenching observed at the excitonic peak (390nm).
Developing Dependable and Secure Cloud Applications
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2016
DOI: 10.1109/MIC.2016.67
Mechanical deformation in silicon by micro-indentation
Publisher: Springer Science and Business Media LLC
Date: 05-2001
Abstract: The mechanical deformation of crystalline silicon induced by micro-indentation has been studied. Indentations were made using a variety of loading conditions. The effects on the final deformation microstructure of the load–unload rates and both spherical and pointed (Berkovich) indenters were investigated at maximum loads of up to 250 mN. The mechanically deformed regions were then examined using cross-sectional transmission electron microscopy (XTEM), Raman spectroscopy, and atomic force microscopy. High-pressure phases (Si-XII and Si-III) and amorphous silicon have been identified in the deformation microstructure of both pointed and spherical indentations. Amorphous Si was observed using XTEM in indentations made by the partial load–unload method, which involves a fast pressure release on final unloading. Loading to the same maximum load using the continuous load cycle, with an approximately four times slower final unloading rate, produced a mixture of Si-XII and Si-III. Slip was observed for all loading conditions, regardless of whether the maximum load exceeded that required to induce “pop-in” and occurs on the {111} planes. Phase transformed material was found in the region directly under the indenter which corresponds to the region of greatest hydrostatic pressure for spherical indentation. Slip is thought to be nucleated from the region of high shear stress under the indenter.
In-situ electrical characterization of Si during nanoindentation
Publisher: Springer Science and Business Media LLC
Date: 2002
Abstract: A novel in-situ electrical characterization technique is used to study the deformation behavior of silicon during nanoindentation. The method involved the formation of a Schottky contact on high resistivity epitaxial Si that is converted to an ohmic contact when Si transforms from the familiar semiconducting Si-I to a metallic Si-II phase. This behavior leads to substantial changes in the current measured across the s le. The Si conductivity used (epitaxial 5 Ωcm on 6 × 10 -3 Ωcm) provides particular sensitivity to the onset of a phase transformation directly under the indenter. On unloading, a reverse transformation from ohmic to Schottky contact was observed. This configuration was used to correlate the observed changes in the electronic properties with features in nanoindentation load-unload curves. The onset of the transformation to the metallic phase was observed to occur during loading using both spherical and Berkovich indenters. Interestingly, the onset of the transformation was detected before the observed discontinuity on loading (the so-called ‘pop-in’ event). This observation is consistent with our previous suggestion that the pop-in event is a result of the onset of flow of the ductile metallic phase beyond the constraint of the indenter. These changes were consistently observed after repeated indentation on the same position in the s le, indicating that small volumes of Si-III and Si-XII crystalline phases as well as amorphous Si (a-Si), which form on unloading, can transform back to the metallic Si-II phase on reloading. A strong decrease in the measured electrical current across the s le occurred as soon as the unloading cycle commenced and prior to the observation of the pop-out event. Overall, these in-situ measurements have provided much insight into pressure-induced transformation in Si under nanoindentation.
Annealing of nanoindentation-induced high pressure crystalline phases created in crystalline and amorphous silicon
Publisher: AIP Publishing
Date: 05-2009
DOI: 10.1063/1.3124366
Abstract: Thermally induced phase transformation of Si-III/Si-XII zones formed by nanoindentation has been studied during low temperature (200& T& °C) thermal annealing by Raman microspectroscopy and transmission electron microscopy. Two sizes of spherical indenter tips have been used to create substantially different volumes of phase transformed zones in both crystalline (c-Si) and amorphous silicon (a-Si) to study the zone size and starting matrix effects. The overall transformation is from Si-III/XII to poly- or nanocrystalline Si-I through intermediate phases of Si-XIII and Si-IV. Attempts have been made to determine the exact transformation pathways. Two scenarios are possible: either Si-XII first transforms to Si-III before transforming to Si-I through the intermediate phases or that Si-XII goes through the intermediate phases while Si-III transforms directly to Si-I. Finally, the phase transformations are slower in the larger indents and the starting matrix (crystalline or amorphous) has a substantial effect on the transformation kinetics of the small indents compared to the larger ones. We attribute this increased stability to both matrix effects (nucleation) and a difference in overall residual stress in indents made in a-Si compared to c-Si.
Runtime recovery actions selection for sporadic operations on public cloud
Publisher: Wiley
Date: 15-07-2016
DOI: 10.1002/SPE.2427
Pathways to exotic metastable silicon allotropes
Publisher: AIP Publishing
Date: 27-09-2016
DOI: 10.1063/1.4962984
Abstract: The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, significant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. This review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner.
Understanding the Unusual Response to High Pressure in KBe2BO3F2
Publisher: Springer Science and Business Media LLC
Date: 22-06-2017
DOI: 10.1038/S41598-017-04323-2
Abstract: Strong anisotropic compression with pressure on the remarkable non-linear optical material KBe 2 BO 3 F 2 has been observed with the linear compression coefficient along the c axis found to be about 40 times larger than that along the a axis. An unusual non-monotonic pressure response was observed for the a lattice parameter. The derived bulk modulus of 31 ± 1 GPa indicates that KBe 2 BO 3 F 2 is a very soft oxide material yet with stable structure up to 45 GPa. A combination of high-pressure synchrotron powder X-ray diffraction, high-pressure Raman spectroscopy, and Density Functional Theory calculations points to the mechanism for the unusual pressure response being due to the competition between the K-F bond length and K-F-K bond angle and the coupling between the stretching and twisting vibration modes.
Accommodating Information Priority Model in Cloudlet Environment
Publisher: Springer International Publishing
Date: 2018
Applying Design Patterns in Smart Contracts
Publisher: Springer International Publishing
Date: 2018
Unchain or Block the Hype? : Decision Drivers, Success Factors, and Perspectives for Blockchain Adoption
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2020
Understanding and Handling Blockchain Uncertainties
Publisher: No publisher found
Date: 2020
An in situ electrical measurement technique via a conducting diamond tip for nanoindentation in silicon
Publisher: Springer Science and Business Media LLC
Date: 03-2007
Abstract: An in situ electrical measurement technique for the investigation of nanoindentation using a Hysitron Triboindenter is described, together with details of experiments to address some technical issues associated with the technique. Pressure-induced phase transformations in silicon during indentation are of particular interest but are not fully understood. The current in situ electrical characterization method makes use of differences in electrical properties of the phase-transformed silicon to better understand the sequence of transformations that occur during loading and unloading. Here, electric current is measured through the s le/indenter tip during indentation, with a fixed or variable voltage applied to the s le. This method allows both current monitoring during indentation and the extraction of current-voltage (I-V) characteristics at various stages of loading. The work presented here focuses on experimental issues that must be understood for a full interpretation of results from nanoindentation experiments in silicon. The tip/s le contact and subsurface electrical resistivity changes dominate the resultant current measurement. Extracting the component of contact resistance provides an extremely sensitive method for measuring the electrical properties of the material immediately below the indenter tip, with initial results from indentation in silicon showing that this is a very sensitive probe of subsurface structural and electrical changes.
R2C: Robust rolling-upgrade in clouds
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2018
ARA-Assessor: Application-Aware Runtime Risk Assessment for Cloud-Based Business Continuity
Publisher: No publisher found
Date: 2017
Contact-induced defect propagation in ZnO
Publisher: AIP Publishing
Date: 10-06-2002
DOI: 10.1063/1.1486264
Abstract: Contact-induced damage has been studied in single-crystal (wurtzite) ZnO by cross-sectional transmission electron microscopy (XTEM) and scanning cathodoluminescence (CL) monochromatic imaging. XTEM reveals that the prime deformation mechanism in ZnO is the nucleation of slip on both the basal and pyramidal planes. Some indication of dislocation pinning was observed on the basal slip planes. No evidence of either a phase transformation or cracking was observed by XTEM in s les loaded up to 50 mN with an ∼4.2 μm radius spherical indenter. CL imaging reveals a quenching of near-gap emission by deformation-produced defects. Both XTEM and CL show that this comparatively soft material exhibits extensive deformation damage and that defects can propagate well beyond the deformed volume under contact. Results of this study have significant implications for the extent of contact-induced damage during fabrication of ZnO-based (opto)electronic devices.
Phase transformation as the single-mode mechanical deformation of silicon
Publisher: AIP Publishing
Date: 22-06-2015
DOI: 10.1063/1.4923205
Abstract: The metastable body-centered cubic (bc8) and rhombohedral (r8) phases of silicon that are formed after the nanoindentation of diamond cubic silicon exhibit properties that are of both scientific and technological interest. This letter demonstrates that large regions of these phases can be readily formed from crystalline silicon via nanoindentation with minimal damage to the surrounding crystal. Cross-sectional transmission electron microscopy is used to show that volumes of these phases 6 μm wide and up to 650 nm deep can be generated using a symmetrical spherical tip of ∼21.5 μm diameter. This result indicates that the use of large symmetrical spherical tips result in highly hydrostatic conditions that can favor the single phase transformation mode without extensive damage to the surrounding crystalline regions that are observed in previous studies.
Experimental observation for new polymorphs of silicon formed through ultrafast-laser-induced microexplosion
Publisher: IEEE
Date: 06-2014
Communication-based approach for promoting energy consumer switching: some evidence from ofgem⇔s database trials in the United Kingdom
Publisher: MDPI AG
Date: 05-08-2020
DOI: 10.3390/EN13195179
Abstract: Prompted by rising concern about weak consumer switching and the practice of price discrimination, over the period of 2016–2019, the Office of Gas and Electricity Markets (Ofgem) undertook a series of trials on communication-based interventions to encourage consumer switching in the United Kingdom. The main purpose of this paper is to assess the experience of these Ofgem trials with a view to draw some lessons for policy makers. The analytical framework adopted for this purpose is informed by existing literature on the barriers for consumer switching. The results of the analysis suggest that while the Ofgem trials have made positive impacts on consumer switching, these impacts varied significantly across the trials, suggesting that some interventions were more effective than others. Further, the overall impacts of the Ofgem trials were moderate, as around 70% of participants did not switch suppliers even in the most impactful trial. This reflects a general lack of understanding in the literature about the behaviour-influencing factors, their impacts, and their context-connects. By implication, the difficulty in stimulating consumer switching, as demonstrated by the Ofgem trials, suggests that weak consumer switching and the practice of price discrimination may simply reflect significant competition, rather than a lack of it, especially if retail margins are not greater than the competitive level. In this case, the communication-based intervention aimed at encouraging consumer switching may lead to further price discrimination, especially for the most vulnerable consumers, who are more likely to stay with their incumbent suppliers.
IoTChain: Establishing Trust in the Internet of Things Ecosystem Using Blockchain
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2018
Blockchain Based Data Integrity Service Framework for IoT Data
Publisher: IEEE
Date: 06-2017
DOI: 10.1109/ICWS.2017.54
An Empirical Study of Cloud API Issues
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2018
Nanoindentation-induced phase transformations in silicon at elevated temperatures
Publisher: IOP Publishing
Date: 11-03-2009
DOI: 10.1088/0957-4484/20/13/135603
Abstract: The nanoindentation-induced phase transformation behavior of silicon at elevated temperatures (25-150 degrees C) has been studied. Nucleation of Si-III/Si-XII on unloading is enhanced with increasing temperature and at the highest temperatures in an amorphous Si matrix, occurs in a continuous fashion without a pop-out event. Interestingly, for slow unloading at the highest temperatures, formation of Si-III/Si-XII in a crystalline Si matrix was not observed. Elevated temperatures enhance the nucleation of Si-III and Si-XII during unloading but the final composition of the phase transformed zone is also dependent on the thermal stability of the phases in their respective matrices.
MAMO: Memory-Augmented Meta-Optimization for Cold-start Recommendation
Publisher: ACM
Date: 20-08-2020
A Data Governance Framework for Platform Ecosystem Process Management
Publisher: No publisher found
Date: 2018
The high pressure phase transformation behavior of silicon nanowires
Publisher: AIP Publishing
Date: 17-09-2018
DOI: 10.1063/1.5048033
Abstract: Si nanowires of 80–150 nm and 200–250 nm diameter are pressurized up to 22 GPa using a diamond anvil cell. Raman and x-ray diffraction data were collected during both compression and decompression. Electron microscopy images reveal that the nanowires retain a nanowire-like morphology (after high pressure treatment). On compression, dc-Si was observed to persist at pressures up to 19 GPa compared to ∼11 GPa for bulk-Si. On decompression, the metallic β-Sn phase was found to be more stable for Si nanowires compared with bulk-Si when lowering the pressure and was observed as low as 6 GPa. For the smallest nanowires studied (80–150 nm), predominately a-Si was obtained on decompression, whereas for larger nanowires (200–250 nm), clear evidence for the r8/bc8-Si phase was obtained. We suggest that the small volume of the in idual Si nanowires compared with bulk-Si inhibits the nucleation of the r8-Si phase on decompression. This study shows that there is a size dependence in the high pressure behavior of Si nanowires during both compression and decompression.
Phase transformation pathways in amorphous germanium under indentation pressure
Publisher: AIP Publishing
Date: 16-04-2014
DOI: 10.1063/1.4871190
Abstract: Nanoindentation-induced phase transformations have been studied in amorphous Ge thin films. These films initially tend to deform via plastic flow of the amorphous phase under load but at a critical pressure a sudden phase transformation occurs. This transformation, to a soft metallic (β-Sn-like)-Ge phase confined under the indenter, is signified by a “pop-in” event on loading. Following “pop-in,” the indentation tests fall into two distinct types of behavior. In one case, the rate of deformation with increasing load after “pop-in” increases, and the observed end-phase following complete unloading is observed to be predominately diamond-cubic Ge. In the other case, the deformation rate (slope of the loading curve) remains the same as that before “pop-in,” and the end phases following unloading are found to contain predominantly unstable r8 and more stable hexagonal Ge phases. The different transformation pathways for these two cases are shown to be related to the probability that the soft (β-Sn-like)-Ge phase volume, which suddenly forms at the transformation pressure, is either unconstrained by the indenter tip (the first case) or totally constrained under the indenter tip (in the latter case).
The structure and electronic properties of tetrahedrally bonded hydrogenated amorphous carbon
Publisher: AIP Publishing
Date: 05-2023
DOI: 10.1063/5.0147494
Abstract: We have synthesized hydrogenated and deuterated amorphous carbon materials that have a density, 2.7 ± 0.1 g/cm3, consistent with almost entirely tetrahedral bonding. In hydrogen-free tetrahedral amorphous carbon, the presence of a minority of sp2 bonded atoms leads to localized states that could be passivated with hydrogen by analogy with hydrogenated amorphous silicon. Neutron diffraction analysis demonstrated that the local bonding environment is consistent with ab initio models of high density hydrogenated tetrahedral amorphous carbon and with the related tetrahedral molecular structure neopentane. The optical bandgap of our material, 4.5 eV, is close to the bandgap in the density of states determined by scanning tunneling spectroscopy (4.3 eV). This bandgap is considerably larger than that of hydrogen-free tetrahedral amorphous carbon, confirming that passivation of sp2 associated tail-states has occurred. Both the structural and electronic measurements are consistent with a model in which the tetrahedrally bonded carbon regions are terminated by hydrogen, causing hopping conductivity to dominate.
The mechanical response of glassy carbon recovered from high pressure
Publisher: AIP Publishing
Date: 14-04-2020
DOI: 10.1063/1.5142309
Abstract: Glassy carbon (GC) is usually considered the prototypical super-elastic material, which can almost fully recover its shape after compression of several gigapascals (GPa). In this work, nanoindentation is used to study the mechanical response of GC, which was subjected to a range of high pressures using a diamond anvil cell (DAC). We show that GC starts to lose its elasticity after compression to 6 GPa and becomes clearly mechanically anisotropic after being compressed beyond ∼30 GPa. Molecular dynamics (MD) simulations are used to calculate Young's modulus before and after compression. Through our experimental results and MD simulations, we show that the elasticity of GC is at a minimum around 30 GPa but recovers after compression to higher pressures along the DAC compression axis.
DevOps and Its Practices
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2016
DOI: 10.1109/MS.2016.81
Adaptive Resource Scheduling in Permissionless Sharded-Blockchains: A Decentralized Multiagent Deep Reinforcement Learning Approach
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2023
Ion-beam-induced reconstruction of amorphous GaN
Publisher: American Physical Society (APS)
Date: 28-02-2001
Applying Design Patterns in Smart Contracts - A Case Study on a Blockchain-Based Traceability Application
Publisher: No publisher found
Date: 2000
Indentation-induced phase transformations in silicon as a function of history of unloading
Publisher: Springer Science and Business Media LLC
Date: 10-2008
Abstract: A crystalline silicon surface, loaded by a Berkovich indenter to a constant maximum load, was unloaded using three unload functions, each consisting of five linear segments of equal time period. The first function had an exponentially decaying unload rate and was found to promote a pop-out event more readily than the second function, having a linear unload rate, or the third case with its unload rate increasing with time. Statistical analyses of experimental data suggest that the unload rate within 20%–30% of the maximum load, when the mean contact pressure in the indent volume is roughly 5 to 6 GPa, is the most dominant factor influencing the probabilistic occurrence of a pop-out event. Unload rates at higher load levels were shown to have a much less significant effect on the probability of pop-out occurrence.
Thermal evolution of the metastable r8 and bc8 polymorphs of silicon
Publisher: Informa UK Limited
Date: 28-01-2015
Thickness-dependent phase transformation in nanoindented germanium thin films
Publisher: IOP Publishing
Date: 30-10-2008
DOI: 10.1088/0957-4484/19/47/475709
Abstract: We investigate the mechanical response of 50-600 nm epitaxial Ge films on a Si substrate using nanoindentation with a nominally spherical (R≈4.3 µm) diamond tip. The inelastic deformation mechanism is found to depend critically on the film thickness. Sub-100 nm Ge films deform by pressure-induced phase transformation, whereas thicker films deform only by shear-induced dislocation slip and twinning. Nanoindentation fracture response is similarly dependent on film thickness. Elastic stress modelling shows that differing stress modes vary in their spatial distribution, and consequently the film thickness governs the stress state in the film, in conjunction with the radius of the nanoindenter tip. This opens the prospect of tailoring the contact response of Ge and related materials in thin film form by varying film thickness and indenter radius.
A Simulation Approach for Studying Behavior and Quality of Blockchain Networks
Publisher: No publisher found
Date: 2018
EvAnGCN: Evolving Graph Deep Neural Network Based Anomaly Detection in Blockchain
Publisher: Springer Nature Switzerland
Date: 2022
Statistically managing cloud operations for latency-tail-tolerance in IoT-enabled smart cities
Publisher: Elsevier BV
Date: 05-2019
Thermal stability of simple tetragonal and hexagonal diamond germanium
Publisher: AIP Publishing
Date: 07-11-2017
DOI: 10.1063/1.5002705
Abstract: Exotic phases of germanium, that form under high pressure but persist under ambient conditions, are of technological interest due to their unique optical and electrical properties. The thermal evolution and stability of two of these exotic Ge phases, the simple tetragonal (st12) and hexagonal diamond (hd) phases, are investigated in detail. These metastable phases, formed by high pressure decompression in either a diamond anvil cell or by nanoindentation, are annealed at temperatures ranging from 280 to 320 °C for st12-Ge and 200 to 550 °C for hd-Ge. In both cases, the exotic phases originated from entirely pure Ge precursor materials. Raman microspectroscopy is used to monitor the phase changes ex situ following annealing. Our results show that hd-Ge synthesized via a pure form of a-Ge first undergoes a subtle change in structure and then an irreversible phase transformation to dc-Ge with an activation energy of (4.3 ± 0.2) eV at higher temperatures. St12-Ge was found to transform to dc-Ge with an activation energy of (1.44 ± 0.08) eV. Taken together with results from previous studies, this study allows for intriguing comparisons with silicon and suggests promising technological applications.
Effect of hydrogen on nanoindentation-induced phase transformations in amorphous silicon
Publisher: AIP Publishing
Date: 15-12-2009
DOI: 10.1063/1.3267853
Abstract: The effect of local hydrogen concentration on nanoindentation-induced phase transformations has been investigated in ion-implanted amorphous silicon (a-Si). Elevated concentrations of H ranging from 5×1018 to 5×1020 cm−3, over the depth of indentation-induced phase transformed zones have been formed in the a-Si by H ion-implantation. Indentation has been performed under conditions that result in phase transformed zones composed totally of Si-III/Si-XII in the “H-free” s les. Deformation during indentation and determination of phase transformation behavior has been examined by analysis of load/unload curves, Raman microspectroscopy, and cross-sectional transmission electron microscopy (XTEM). With increasing H content, the probability of forming Si-III/Si-XII and the volume fraction of Si-III/Si-XII decrease. XTEM shows that these reduced volumes are randomly distributed within the phase transformed zone and are surrounded by indentation-induced a-Si. For a H concentration of 5×1020 cm−3, the probability of forming Si-III/Si-XII is reduced to 0.5 compared to 1 in “H-free” material and for those indents that exhibit the Si-III/Si-XII end phase the volume fraction is approximately 60 %. We suggest that the monohydride bonding configuration of Si and H in a-Si reduces the formation of the high pressure crystalline phases by retarding growth of the crystallites through a similar mechanism to that of hydrogen-retarded solid phase crystallization of a-Si to diamond cubic crystalline Si-I phase.
Impurity-free seeded crystallization of amorphous silicon by nanoindentation
Publisher: AIP Publishing
Date: 15-10-2011
DOI: 10.1063/1.3647587
Abstract: We demonstrate that nanoindents formed in amorphous Si films, with dimensions as small as ∼20 nm, provide a means to seed solid phase crystallization. During post-indentation annealing at ∼600 °C, solid phase crystallization initiates from the indented sites, effectively removing the incubation time for random nucleation in the absence of seeds. The seeded crystallization is studied by optical microscopy, cross-sectional transmission electron microscopy, and electrical characterization via Hall measurements. Full crystallization can be achieved, with improved electrical characteristics attributed to the improved microstructure, using a lower thermal budget. The process is metal contaminant free and allows for selective area crystallization.
The mechanical properties of energetically deposited non-crystalline carbon thin films
Publisher: Elsevier BV
Date: 03-2016
Heterogeneity of carbon fibre
Publisher: Elsevier BV
Date: 03-2014
The indentation hardness of silicon measured by instrumented indentation: What does it mean?
Publisher: Springer Science and Business Media LLC
Date: 05-12-2012
DOI: 10.1557/JMR.2012.389
Mechanical properties of ZnO epitaxial layers grown on a- and c-axis sapphire
Publisher: AIP Publishing
Date: 11-05-2005
DOI: 10.1063/1.1929874
Abstract: The mechanical properties of zinc oxide epitaxial layers grown on a- and c-axis sapphire have been studied by spherical nanoindentation and cross-sectional transmission electron microscopy. As-grown threading dislocations, which are characteristic of epitaxial material, combined with the presence of the much harder, underlying substrate are found to have a significant effect on the mechanical behavior of ZnO epilayers as compared to bulk material. Epilayer material is found to be significantly harder than its bulk counterpart. For a-axis epilayers, analysis of load–unload data yields a hardness of 6.6±1.2GPa, and 5.75±0.8GPa for c-axis layers. We attribute this increased hardness to strain compensation via the presence of as-grown defects. These defects inhibit the slip mechanism responsible for relative softness of bulk single crystals. The absence of pop-in events from analyzed continuous-load nanoindentation data is further evidence for strain compensation by native defects within the epilayers. Large variations in the spread of collected data are indicative of inhomegenity in the epilayers.
Understanding and Handling Blockchain Uncertainties
Publisher: Springer International Publishing
Date: 2020
Temperature dependence of Raman scattering from the high-pressure phases of Si induced by indentation
Publisher: American Physical Society (APS)
Date: 06-06-2011
Process-Oriented Non-intrusive Recovery for Sporadic Operations on Cloud
Publisher: IEEE
Date: 06-2016
DOI: 10.1109/DSN.2016.17
Deformation behavior of ion-irradiated polyimide
Publisher: AIP Publishing
Date: 27-07-2004
DOI: 10.1063/1.1776618
Abstract: We study nanoindentation hardness, Young’s modulus, and tensile strength of polyimide (Kapton H) films bombarded with MeV light ions in the predominantly electronic stopping power regime. Results show that, for all the ion irradiation conditions studied, bombardment increases the hardness and Young’s modulus and decreases the tensile strength. These changes depend close to linearly on ion fluence and superlinearly (with a power-law exponent factor of ∼1.5) on electronic energy loss. Physical mechanisms of radiation-induced changes to mechanical properties of polyimide are discussed.
The shear-driven transformation mechanism from glassy carbon to hexagonal diamond
Publisher: Elsevier BV
Date: 02-2019
Response to “Comment on ‘Phase transformations induced in relaxed amorphous silicon by indentation at room temperature’ ” [Appl. Phys. Lett. 87, 016102 (2005)]
Publisher: AIP Publishing
Date: 07-2005
DOI: 10.1063/1.1992664
Adversarial dual autoencoders for trust-aware recommendation
Publisher: Springer Science and Business Media LLC
Date: 27-01-2021
Dependence of short and intermediate-range order on preparation in experimental and modeled pure a-Si
Publisher: Elsevier BV
Date: 04-2016
Pop-in events induced by spherical indentation in compound semiconductors
Publisher: Springer Science and Business Media LLC
Date: 2004
DOI: 10.1557/JMR.2004.19.1.380
Abstract: Details of the elastic–plastic transitions in crystalline compound semiconductors have been examined using spherical indentation. Two cubic (InP and GaAs) and two hexagonally structured semiconductors (ZnO and GaN) have been studied. A series of indentations have been made in each material at a number of different loads. The resulting load–penetration curves exhibited one or more discontinuities on loading (so called pop-in events). The load at which the initial pop-in event occurred has been measured along with the corresponding indenter extension. The elastic and elastic–plastic response of each material to spherical indentation has been calculated and compared with the experiment. By taking the difference between the elastic and elastic–plastic penetration depths, it has been found that the pop-in extension at each load could be predicted for each material. The detailed deformation behavior of each of the materials during indentation has also been discussed.
Trans-Regime Structural Transition of (In3+ + Nb5+) Co-Doped Anatase TiO2 Nanocrystals under High Pressure
Publisher: American Chemical Society (ACS)
Date: 04-04-2017
Temperature dependent deformation mechanisms in pure amorphous silicon
Publisher: AIP Publishing
Date: 21-03-2014
DOI: 10.1063/1.4869136
Abstract: High temperature nanoindentation has been performed on pure ion-implanted amorphous silicon (unrelaxed a-Si) and structurally relaxed a-Si to investigate the temperature dependence of mechanical deformation, including pressure-induced phase transformations. Along with the indentation load-depth curves, ex situ measurements such as Raman micro-spectroscopy and cross-sectional transmission electron microscopy analysis on the residual indents reveal the mode of deformation under the indenter. While unrelaxed a-Si deforms entirely via plastic flow up to 200 °C, a clear transition in the mode of deformation is observed in relaxed a-Si with increasing temperature. Up to 100 °C, pressure-induced phase transformation and the observation of either crystalline (r8/bc8) end phases or pressure-induced a-Si occurs in relaxed a-Si. However, with further increase of temperature, plastic flow rather than phase transformation is the dominant mode of deformation. It is believed that the elevated temperature and pressure together induce bond softening and “defect” formation in structurally relaxed a-Si, leading to the inhibition of phase transformation due to pressure-releasing plastic flow under the indenter.
Sharing Deep Neural Network Models with Interpretation
Publisher: ACM Press
Date: 2018
DeepCU: Integrating both common and unique latent information for multimodal sentiment analysis
Publisher: International Joint Conferences on Artificial Intelligence Organization
Date: 08-2019
Abstract: Multimodal sentiment analysis combines information available from visual, textual, and acoustic representations for sentiment prediction. The recent multimodal fusion schemes combine multiple modalities as a tensor and obtain either the common information by utilizing neural networks, or the unique information by modeling low-rank representation of the tensor. However, both of these information are essential as they render inter-modal and intra-modal relationships of the data. In this research, we first propose a novel deep architecture to extract the common information from the multi-mode representations. Furthermore, we propose unique networks to obtain the modality-specific information that enhances the generalization performance of our multimodal system. Finally, we integrate these two aspects of information via a fusion layer and propose a novel multimodal data fusion architecture, which we call DeepCU (Deep network with both Common and Unique latent information). The proposed DeepCU consolidates the two networks for joint utilization and discovery of all-important latent information. Comprehensive experiments are conducted to demonstrate the effectiveness of utilizing both common and unique information discovered by DeepCU on multiple real-world datasets. The source code of proposed DeepCU is available at verma88/DeepCU-IJCAI19.
Room temperature writing of electrically conductive and insulating zones in silicon by nanoindentation
Publisher: AIP Publishing
Date: 31-01-2011
DOI: 10.1063/1.3549191
Abstract: Conventional silicon devices are fabricated in the diamond cubic phase of silicon, so-called Si-I. Other phases of silicon such as Si-XII and Si-III can be formed under pressure applied by nanoindentation and these phases are metastable at room temperature and pressure. We demonstrate in this letter that such phases exhibit different electrical properties to normal (diamond cubic) silicon and exploit this to perform maskless, room temperature, electrical patterning of silicon by writing both conductive and insulating zones directly into silicon substrates by nanoindentation. Such processing opens up a number of potentially new applications without the need for high temperature processing steps.
Hexagonal germanium formed via a pressure-induced phase transformation of amorphous germanium under controlled nanoindentation
Publisher: Wiley
Date: 21-03-2013
A Differentiated Caching Mechanism to Enable Primary Storage Deduplication in Clouds
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2018
Hybrid Collaborative Recommendation via Semi-AutoEncoder
Publisher: Springer International Publishing
Date: 2017
Unraveling Metric Vector Spaces With Factorization for Recommendation
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2019
Deformation behavior of ion-beam-modified GaN
Publisher: AIP Publishing
Date: 08-01-2001
DOI: 10.1063/1.1335552
Abstract: The deformation behavior of wurtzite GaN films modified by ion bombardment is studied by nanoindentation with a spherical indenter. Results show that implantation disorder significantly changes the mechanical properties of GaN. In particular, GaN amorphized by ion bombardment exhibits plastic deformation even for very low loads with dramatically reduced values of hardness and Young’s modulus compared to the values of as-grown GaN. Implantation-produced defects in crystalline GaN suppress the plastic component of deformation and significantly change the values of hardness and Young’s modulus. In addition, implantation disorder in crystalline GaN suppresses both “pop-in” events during loading and the appearance of slip traces on the s le surface as a result of indentation. This strongly suggests that slip nucleation (rather than a phase transformation) is the physical mechanism responsible for the pop-in events observed during loading of as-grown crystalline GaN.
Nanoindentation-induced phase transformation in relaxed and unrelaxed ion-implanted amorphous germanium
Publisher: AIP Publishing
Date: 11-2009
DOI: 10.1063/1.3255999
Abstract: We have investigated nanoindentation-induced plastic deformation in amorphous germanium (a-Ge) prepared by high-energy self-ion implantation. Using cross-sectional transmission electron microscopy, micro-Raman spectroscopy, and force-displacement curve analysis, we find strong evidence for a pressure-induced metallic phase transformation during indentation. Crystalline diamond-cubic Ge-I is observed in residual indents. Relaxed and unrelaxed structural states of a-Ge exhibit similar behavior on loading, but transform at different pressures on unloading. Both forms are markedly softer mechanically than crystalline Ge. These results assist in furthering the understanding of the intriguing phenomenon known as “explosive crystallization.”
In situelectrical characterization of phase transformations in Si during indentation
Publisher: American Physical Society (APS)
Date: 28-02-2003
A Pattern Language for Blockchain Governance
Publisher: ACM
Date: 06-07-2022
uBaaS: A unified blockchain as a service platform
Publisher: Elsevier BV
Date: 12-2019
One Size Does Not Fit All: The Case for Chunking Configuration in Backup Deduplication
Publisher: IEEE
Date: 05-2018
Giant pop-ins and amorphization in germanium during indentation
Publisher: AIP Publishing
Date: 15-02-2007
DOI: 10.1063/1.2490563
Abstract: Sudden excursions of unusually large magnitude (& μm), “giant pop-ins,” have been observed in the force-displacement curve for high load indentation of crystalline germanium (Ge). A range of techniques including Raman microspectroscopy, focused ion-beam cross sectioning, and transmission electron microscopy, are applied to study this phenomenon. Amorphous material is observed in residual indents following the giant pop-in. The giant pop-in is shown to be a material removal event, triggered by the development of shallow lateral cracks adjacent to the indent. Enhanced depth recovery, or “elbowing,” observed in the force-displacement curve following the giant pop-in is explained in terms of a compliant response of plates of material around the indent detached by lateral cracking. The possible causes of amorphization are discussed, and the implications in light of earlier indentation studies of Ge are considered.
Confined micro-explosion induced by ultrashort laser pulse at SiO2/Si interface
Publisher: Springer Science and Business Media LLC
Date: 30-11-2013
The Intersection of Continuous Deployment and Architecting Process
Publisher: ACM
Date: 08-09-2016
Nanoengineering mechanically robust aerogels via control of foam morphology
Publisher: AIP Publishing
Date: 24-07-2006
DOI: 10.1063/1.2236222
Abstract: Potential of aerogels for technological applications is often limited by their poor mechanical properties. Here, we demonstrate that alumina aerogel monoliths with excellent mechanical properties can be made by controlling the crystallographic phase, shape, and size of nanoligaments. In particular, we show that thermal processing of aerogels with a morphology of interconnected nanoleaflets causes dehydration and associated curling of the nanoleaflets, resulting in a dramatic improvement of mechanical properties. This study shows an effective way to control mechanical properties of the nanoporous solids that can be synthesized with ligaments having a quasi-two-dimensional shape, such as platelets, ribbons, or leaflets.
Phase transformations induced in relaxed amorphous silicon by indentation at room temperature
Publisher: AIP Publishing
Date: 06-12-2004
DOI: 10.1063/1.1832757
Abstract: The deformation behavior of self-ion-implanted amorphous-Si (a-Si) has been studied using spherical nanoindentation in both relaxed (annealed) and unrelaxed (as-implanted) a-Si. Interestingly, phase transformations were clearly observed in the relaxed state, with the load–unload curves from these s les displaying characteristic discontinuities and cross-sectional transmission electron microscopy images indicating the presence of high-pressure crystalline phases Si-III and Si-XII following pressure release. Thus, an amorphous to crystalline phase transformation has been induced by indentation at room temperature. In contrast, no evidence of a phase transformation was observed in unrelaxed a-Si, which appeared to deform via plastic flow of the amorphous phase. Furthermore, in situ electrical measurements clearly indicate the presence of a metallic Si phase during loading of relaxed a-Si but no such behavior was observed for unrelaxed a-Si
An empirical study of architecting for continuous delivery and deployment
Publisher: Springer Science and Business Media LLC
Date: 08-09-2018
A RESTful architecture for data exploration as a service
Publisher: ACM
Date: 08-04-2019
Beyond Continuous Delivery: An Empirical Investigation of Continuous Deployment Challenges
Publisher: IEEE
Date: 11-2017
DOI: 10.1109/ESEM.2017.18
High pressure crystalline phase formation during nanoindentation: Amorphous versus crystalline silicon
Publisher: AIP Publishing
Date: 28-08-2006
DOI: 10.1063/1.2339039
Abstract: Phase transformations induced by indentation at different unloading rates have been studied in crystalline and amorphous silicon via Raman microspectroscopy and transmission electron microscopy. Unloading was performed at a “slow” rate of ∼0.9mN∕s which is known to create volumes of high pressure phases (Si-III and Si-XII) in crystalline silicon as well as “rapid” unloading (∼1000mN∕s), where amorphous phases are expected. Stark differences between the resulting structures are observed depending on whether the starting material is amorphous or crystalline silicon. Interestingly, amorphous silicon transforms to high pressure phases much more readily than crystalline silicon even after rapid unloading.
Mechanical properties of tungsten following rhenium ion and helium plasma exposure
Publisher: Elsevier BV
Date: 08-2017
Segregation and precipitation of Er in Ge
Publisher: AIP Publishing
Date: 28-05-2007
DOI: 10.1063/1.2743881
Abstract: Although Er-doped Ge nanomaterials are attractive for photonic applications, very little is known about the basic properties of Er in Ge. Here, the authors study the annealing behavior of Ge implanted with keV Er ions to doses resulting in ≲1at.% of Er. Large redistribution of Er, with segregation at the amorphous/crystalline interface, starts at ≳500°C, while lower temperatures are required for material recrystallization. However, even at 400°C, Er forms precipitates. The concentration of Er trapped in the bulk after recrystallization decreases with increasing temperature but is independent of the initial bulk Er concentration for the range of ion doses studied here.
Thermal evolution of the indentation-induced phases of silicon
Publisher: AIP Publishing
Date: 09-09-2019
DOI: 10.1063/1.5108751
Abstract: Novel phases of Si that are predicted to have industrially desirable properties can be recovered after indentation-induced pressure. However, the thermal stability of these phases is not well understood. Furthermore, in the past, different methods of annealing have resulted in conflicting reports on annealing stability and transformation pathways. This study investigates the thermal stability of several metastable Si phases called r8-Si, bc8-Si, hd-Si, and Si-XIII under furnace annealing, incremental annealing, and laser annealing using Raman microspectroscopy and electron diffraction. The temperature range of stability for these metastable phases is thus determined. Of particular interest, hd-Si is stable to a much higher temperature than previously reported, being the predominant phase observed in this study after annealing at 450 °C. This finding was enabled through a new method for confirming the presence of hd-Si by detailed electron diffraction. This high thermal stability generates renewed interest in exploiting this phase for industrial applications, such as strain-tailored solar absorption.
Data Service API Design for Data Analytics
Publisher: No publisher found
Date: 2018
Graphitization of Glassy Carbon after Compression at Room Temperature
Publisher: American Physical Society (APS)
Date: 23-05-2018
Bimetallic Ions Codoped Nanocrystals: Doping Mechanism, Defect Formation, and Associated Structural Transition
Publisher: American Chemical Society (ACS)
Date: 05-07-2017
Hardness of nano- and microcrystalline lonsdaleite
Publisher: AIP Publishing
Date: 20-02-2023
DOI: 10.1063/5.0138911
Abstract: Lonsdaleite is a hexagonal allotrope of carbon found in nature in meteorites and at meteorite impact sites. It has been predicted to have an indentation hardness greater than cubic diamond by first principles calculations. However, this has not been demonstrated experimentally. Here, nanoindentation was used to measure the hardness of two different lonsdaleite s les. One contains nanocrystalline lonsdaleite synthesized by high pressure compression of glassy carbon. The other is from a ureilite meteorite that contains lonsdaleite crystals up to ∼1 μm. The hardness of these two s les was determined using both the Oliver–Pharr and Meyer methods. Our results show that the hardness of the lonsdaleite s les is similar to that of diamond therefore, there is no evidence that these forms of polycrystalline lonsdaleite are significantly harder than similar forms of diamond.
Hybrid Collaborative Recommendation via Semi-AutoEncoder
Publisher: No publisher found
Date: 2017
Benzannulated 6,5-Spiroketals from Donor–Acceptor Cyclopropanes
Publisher: American Chemical Society (ACS)
Date: 29-03-2019
DOI: 10.1021/ACS.ORGLETT.9B00878
Abstract: A rapid and facile synthesis of benzannulated 6,5-spiroketals from vinyl 1,1-diacylcyclopropanes is reported. The method utilizes mild reaction conditions with good to excellent yields and high diastereoselectivity. This methodology was then used to construct the core of berkelic acid.
Hybrid Networks: Improving Deep Learning Networks via Integrating Two Views of Images
Publisher: Springer International Publishing
Date: 2018
Effect of oxygen concentration on nanoindentation-induced phase transformations in ion-implanted amorphous silicon
Publisher: AIP Publishing
Date: 15-04-2009
DOI: 10.1063/1.3097752
Abstract: The effect of the local oxygen concentration in ion-implanted amorphous Si (a-Si) on nanoindentation-induced phase transformations has been investigated. Implantation of oxygen into the a-Si films has been used to controllably introduce an approximately constant concentration of oxygen, ranging from ∼1018 to ∼1021 cm−3, over the depth range of the phase transformed zones. Nanoindentation was performed under conditions that ensure a phase transformed zone composed completely of Si-III/XII in the nominally oxygen-free a-Si. The effect of the local oxygen concentration has been investigated by analysis of the unloading curves, Raman microspectroscopy, and cross-sectional transmission electron microscopy (XTEM). The formation of Si-III/XII is suppressed with increasing oxygen concentration, favoring a greater volume of a-Si within the zones. The Raman microspectroscopy and XTEM verify that the volume of Si-III/XII decreases with increasing O concentration. With the smaller volumes of Si-III/XII, the pop-out normally observed on load versus penetration depth curves during unloading decreases in magnitude, becoming more kinklike and is barely discernable at high concentrations of oxygen. The probability of forming any high pressure phases is reduced from 1 to ∼0.1 for a concentration of 1021 cm−3. We suggest that the bonding of O with Si reduces the formation of Si-III/XII during unloading through a similar mechanism to that of oxygen-retarded solid phase crystallization of a-Si.
Unexpected short- and medium-range atomic structure of sputtered amorphous silicon upon thermal annealing
Publisher: AIP Publishing
Date: 11-2011
DOI: 10.1063/1.3658628
Abstract: We investigate the structure of magnetron-sputtered (MS) amorphous silicon (a-Si) prepared under standard deposition conditions and compare this to pure ion-implanted (II) a-Si. The structure of both films is characterized in their as-prepared and thermally annealed states. Significant differences are observed in short- and medium-range order following thermal annealing. Whereas II a-Si undergoes structural relaxation toward a continuous random network, MS a-Si exhibits little change. Cross-sectional transmission electron microscopy reveals the presence of nanopores in the MS film consistent with reduced mass-density. Therefore, the short- and medium-range order of annealed, MS a-Si is tentatively attributed to these pores.
Nanoindentation of epitaxial GaN films
Publisher: AIP Publishing
Date: 20-11-2000
DOI: 10.1063/1.1328047
Abstract: Wurtzite GaN films grown on sapphire substrates are studied by nanoindentation with a spherical indenter. No systematic dependence of the mechanical properties of GaN epilayers on the film thickness (at least for thicknesses from 1.8 to 4 μm) as well as on doping type is observed. Slip is identified as one of the physical mechanisms responsible for plastic deformation of GaN and may also contribute to the “pop-in” events observed during loading. No visible material cracking is found even after indentations at high loads (900 mN), but a pronounced elevation of the material surrounding the impression is observed.
Patterning of silicon by indentation and chemical etching
Publisher: AIP Publishing
Date: 17-09-2007
DOI: 10.1063/1.2779111
Abstract: An array of features on Si (100) is fabricated by a new maskless pattering process involving a combination of indentation and anisotropic wet chemical etching. Indentation is carried out in order to induce transformation to the high-pressure phases, Si III and Si XII, before etching in a KOH solution. The pressure-induced phases are found to be highly resistant to etching in the KOH solution, with an etch rate more than an order of magnitude slower than that of Si (100). The possibility of exploiting this mechanism for a maskless nanoscale patterning process in Si using indentation is discussed.
Experimental evidence for semiconducting behavior of Si-XII
Publisher: American Physical Society (APS)
Date: 25-02-2011
In situspectroscopic study of the plastic deformation of amorphous silicon under nonhydrostatic conditions induced by indentation
Publisher: American Physical Society (APS)
Date: 17-12-2015
HDM: A Composable Framework for Big Data Processing
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2018
Experimental evidence of new tetragonal polymorphs of silicon formed through ultrafast laser-induced confined microexplosion
Publisher: Springer Science and Business Media LLC
Date: 29-06-2015
DOI: 10.1038/NCOMMS8555
Abstract: Ordinary materials can transform into novel phases at extraordinary high pressure and temperature. The recently developed method of ultrashort laser-induced confined microexplosions initiates a non-equilibrium disordered plasma state. Ultra-high quenching rates overcome kinetic barriers to the formation of new metastable phases, which are preserved in the surrounding pristine crystal for subsequent exploitation. Here we demonstrate that confined microexplosions in silicon produce several metastable end phases. Comparison with an ab initio random structure search reveals six energetically competitive potential phases, four tetragonal and two monoclinic structures. We show the presence of bt8 and st12, which have been predicted theoretically previously, but have not been observed in nature or in laboratory experiments. In addition, the presence of the as yet unidentified silicon phase, Si-VIII and two of our other predicted tetragonal phases are highly likely within laser-affected zones. These findings may pave the way for new materials with novel and exotic properties.
Nanoindentation of ion-implanted crystalline germanium
Publisher: American Physical Society (APS)
Date: 22-09-2009
Formation and growth of nanoindentation-induced high pressure phases in crystalline and amorphous silicon
Publisher: AIP Publishing
Date: 15-09-2007
DOI: 10.1063/1.2781394
Abstract: Nanoindentation-induced formation of high pressure crystalline phases (Si-III and Si-XII) during unloading has been studied by Raman micro-spectroscopy, cross-sectional transmission electron microscopy (XTEM), and postindentation electrical measurements. For indentation in crystalline silicon (c-Si), rapid unloading (∼1000 mN∕s) results in the formation of amorphous silicon (a-Si) only a result we have exploited to quench the formation of high pressure phases at various stages during unloading to study their formation and evolution. This reveals that seed volumes of Si-III and Si-XII form during the early stages of unloading with substantial volumes only forming after the pop-out event that occurs at about 50% of the maximum load. In contrast, high pressure phases form much more readily in an a-Si matrix, with substantial volumes forming without an observable pop-out event with rapid unloading. Postindentation electrical measurements have been used to further investigate the end phases and to identify differences between indentations which otherwise appear to be identical from the XTEM and Raman analyses.
Accommodating Information Priority Model in Cloudlet Environment
Publisher: No publisher found
Date: 2017
Indentation-induced damage in GaN epilayers
Publisher: AIP Publishing
Date: 21-01-2002
DOI: 10.1063/1.1436280
Abstract: The mechanical deformation of wurtzite GaN epilayers grown on sapphire substrates is studied by spherical indentation, cross-sectional transmission electron microscopy (XTEM), and scanning cathodoluminescence (CL) monochromatic imaging. CL imaging of indents which exhibit plastic deformation (based on indentation data) shows an observable “footprint” of deformation-produced defects that result in a strong reduction in the intensity of CL emission. Multiple discontinuities are observed during loading when the maximum load is above the elastic-plastic threshold, and such a behavior can be correlated with multiple slip bands revealed by XTEM. No evidence of pressure-induced phase transformations is found from within the mechanically damaged regions using selected-area diffraction patterns. The main deformation mechanism appears to be the nucleation of slip on the basal planes, with dislocations being nucleated on additional planes on further loading. XTEM reveals no cracking or delamination in any of the s les studied for loads of up to 250 mN.
Understanding pressure-induced phase-transformation behavior in silicon through in situ electrical probing under cyclic loading conditions
Publisher: AIP Publishing
Date: 15-05-2009
DOI: 10.1063/1.3130154
Abstract: Cyclic indentation of crystalline silicon exhibits interesting pressure-induced phase-transformation behavior whereby sequential changes in the phase composition ultimately lead to a catastrophic (“pop-out”) event during subsequent cycles and complete transformation to high pressure Si-III and Si-XII phases. This study combines in situ electrical measurements with cyclic loading to monitor such phase-transformation behavior. We find that, if a pop-out is not observed on the unloading curve, the end phase is predominantly amorphous but a small and increasing volume of Si-III/Si-XII results with each cycle. At a critical Si-III/Si-XII volume, pop-out can occur on a subsequent cycle, whereafter Si-III/Si-XII dominates the indent volume.
Attn-HybridNet: Improving Discriminability of Hybrid Features With Attention Fusion
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2021
Nanoindentation-induced phase transformation in crystalline silicon and relaxed amorphous silicon
Publisher: Elsevier BV
Date: 06-2007
Designing blockchain-based applications a case study for imported product traceability
Publisher: Elsevier BV
Date: 03-2019
Nanoindentation of Si Nanocrystals in SiO_2
Publisher: IEEE
Date: 2005
Giant pop-ins in nanoindented silicon and germanium caused by lateral cracking
Publisher: Springer Science and Business Media LLC
Date: 02-2008
Abstract: Giant “pop-in” displacements are observed in crystalline silicon and germanium during high-load nanoindentation with a spherical diamond tip. These events are consistent with material removal triggered by lateral cracking during loading, which poses a hazard to microelectromechanical systems (MEMS) operation. We examine the scaling of the pop-in displacements as a function of peak indentation load and demonstrate a correlation with the depth of the plastic contact zone. We argue that giant pop-ins may occur in a broad range of highly brittle materials.
Quantitative electromechanical characterization of materials using conductive ceramic tips
Publisher: Elsevier BV
Date: 06-2014
Prompt-tuned Code Language Model as a Neural Knowledge Base for Type Inference in Statically-Typed Partial Code
Publisher: ACM
Date: 10-10-2022
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