ORCID Profile
0000-0002-3990-0474
Current Organisations
Maryville University
,
Ruhr-Universität Bochum
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Publisher: American Chemical Society (ACS)
Date: 24-02-2020
Publisher: IOP Publishing
Date: 20-11-2014
DOI: 10.1088/0957-4484/25/49/495702
Abstract: Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active in idual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (E(b)xx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of E(b)xx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and E(b)xx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative E(b)xx = -15.5 meV.
Publisher: Emerald
Date: 07-06-2023
Abstract: While Six Sigma (SS) has been deployed effectively in Indian manufacturing and service sectors as a process improvement methodology, the implementation of Design for Six Sigma (DFSS) for robust product and service development has not shown noticeable results. Therefore, this article aims to determine the critical failure factors (CFFs) of DFSS in the Indian context. The paper presents the results of a pilot survey on the CFFs of DFSS in Indian companies. The survey participants were specialists in DFSS who have been involved in DFSS projects in their past and present companies. Moreover, the pilot study participants were DFSS Ch ions, Master Black Belts, Black Belts and Green Belts from the manufacturing and service sectors. Company-wide applications of DFSS are very limited in India. Most of the DFSS project failures are reported in the Analyse phase of the project. The results indicated that all 18 CFFs used in the survey have a significant impact on project failures. Also, it was determined that all CFFs are positively correlated with each other. Further, a strong correlation was observed between the voice of the customer (VOC) and project selection and prioritisation. In addition, effective training showed a strong correlation with the right selection of tools. The pilot survey was based on a limited s le size. Moreover, the study is confined to only the Indian context and data were collected through the authors' networks. However, respondents were proficient, certified and involved in DFSS project deployment in the manufacturing and service sectors. Therefore, the study's findings are useful and meaningful to draw robust inferences. To the best of the authors' knowledge, this is the first empirical study conducted in the Indian context to identify the reasons for DFSS project failures. The study's findings can aid academicians and practitioners in comprehending and critically examining the CFFs of DFSS before executing a project. Moreover, the research outcome motivates policymakers to create an ecosystem to effectively adopt DFSS for start-ups and micro, small and medium enterprises (MSME) to ensure a circular economy and support the “Atmanirbhar Bharat” initiative.
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 11-2015
Publisher: MDPI AG
Date: 07-04-2018
DOI: 10.3390/NANO8040223
Abstract: GaN nanorods, essentially free from crystal defects and exhibiting very sharp band-edge luminescence, have been grown by reactive direct-current magnetron sputter epitaxy onto Si (111) substrates at a low working pressure of 5 mTorr. Upon diluting the reactive N2 working gas with a small amount of Ar (0.5 mTorr), we observed an increase in the nanorod aspect ratio from 8 to ~35, a decrease in the average diameter from 74 to 35 nm, and a two-fold increase in nanorod density. With further dilution (Ar = 2.5 mTorr), the aspect ratio decreased to 14, while the diameter increased to 60 nm and the nanorod density increased to a maximum of 2.4 × 109 cm−2. Yet, lower N2 partial pressures eventually led to the growth of continuous GaN films. The observed morphological dependence on N2 partial pressure is explained by a change from N-rich to Ga-rich growth conditions, combined with reduced GaN-poisoning of the Ga-target as the N2 gas pressure is reduced. Nanorods grown at 2.5 mTorr N2 partial pressure exhibited a high intensity 4 K photoluminescence neutral donor bound exciton transitions (D0XA) peak at ~3.479 eV with a full-width-at-half-maximum of 1.7 meV. High-resolution transmission electron microscopy corroborated the excellent crystalline quality of the nanorods.
Publisher: AIP Publishing
Date: 11-11-2013
DOI: 10.1063/1.4830044
Abstract: Nucleation mechanism of catalyst-free GaN nanorod grown on Si(111) is investigated by the fabrication of uniform and narrow (& nm) nanorods without a pre-defined mask by molecular beam epitaxy. Direct evidences show that the nucleation of GaN nanorods stems from the sidewall of the underlying islands down to the Si(111) substrate, different from commonly reported ones on top of the island directly. Accordingly, the growth and density control of the nanorods is exploited by a “narrow-pass” approach that only narrow nanorod can be grown. The optimal size of surrounding non-nucleation area around single nanorod is estimated as 88 nm.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0SC05990K
Abstract: The stability of bimetallic AgCu and PdCu catalysts for electrochemical CO 2 RR is investigated using the combination of operando and ex situ TEM. The local CO concentration is identified as the main link between activity, stability and selectivity.
Publisher: Informa UK Limited
Date: 18-12-2022
Publisher: AIP Publishing
Date: 25-02-2016
DOI: 10.1063/1.4942664
Abstract: The phase formation in the boron-rich section of the Al-Y-B system has been explored by a correlative theoretical and experimental research approach. The structure of coatings deposited via high power pulsed magnetron sputtering from a compound target was studied using elastic recoil detection analysis, electron energy loss spectroscopy spectrum imaging, as well as X-ray and electron diffraction data. The formation of AlYB14 together with the (Y,Al)B6 impurity phase, containing 1.8 at. % less B than AlYB14, was observed at a growth temperature of 800 °C and hence 600 °C below the bulk synthesis temperature. Based on quantum mechanical calculations, we infer that minute compositional variations within the film may be responsible for the formation of both icosahedrally bonded AlYB14 and cubic (Y,Al)B6 phases. These findings are relevant for synthesis attempts of all boron rich icosahedrally bonded compounds with the space group: Imma that form ternary phases at similar compositions.
Publisher: Informa UK Limited
Date: 22-11-2022
Location: United States of America
No related grants have been discovered for Elizabeth Cudney.