ORCID Profile
0000-0002-4641-8977
Current Organisations
CSIRO
,
RMIT University
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Publisher: IEEE
Date: 06-2006
Publisher: IEEE
Date: 11-2009
Publisher: IEEE
Date: 06-2006
Publisher: IOP Publishing
Date: 06-2021
Abstract: With its monoelemental composition, various crystalline forms and an inherently strong spin–orbit coupling, bismuth has been regarded as an ideal prototype material to expand our understanding of topological electronic structures. In particular, two-dimensional bismuth thin films have attracted a growing interest due to potential applications in topological transistors and spintronics. This calls for an effective physical model to give an accurate interpretation of the novel topological phenomena shown by two-dimensional bismuth. However, the conventional semi-empirical approach of adapting bulk bismuth hoppings fails to capture the topological features of two-dimensional bismuth allotropes because the electronic band topology is heavily influenced by crystalline symmetries. Here we provide a new parameterization using localized Wannier functions derived from the Bloch states in first-principles calculations. We construct new tight-binding models for three types of two-dimensional bismuth allotropes: a Bi (111) bilayer, bismuthene and a Bi (110) bilayer. We demonstrate that our tight-binding models can successfully reproduce the electronic and topological features of these two-dimensional allotropes. Moreover, these tight-binding models can be used to explain the physical origin of the occurrence of novel band topology and the perturbation effects in these bismuth allotropes. In addition, these models can serve as a starting point for investigating the electron/spin transport and electromagnetic response in low-dimensional topological devices.
Publisher: American Physical Society (APS)
Date: 11-03-2021
Publisher: IOP Publishing
Date: 22-01-2014
DOI: 10.1088/0953-8984/26/6/065302
Abstract: Using the Burt-Foreman envelope function theory and effective mass approximation, we develop a theoretical model for an arbitrary number of interacting donor atoms embedded in silicon which reproduces the electronic energy spectrum with high computational efficiency, taking into account the effective mass anisotropy and the valley-orbit coupling. We show that the variation of the relative magnitudes of the electronic coupling between the donor atoms with respect to the valley-orbit coupling as a function of the internuclear distance leads to different kinds of spatial interference patterns of the wavefunction. We also report on the impact of the orientation of the diatomic phosphorus donor molecular ion in the crystal lattice on the ionization energy and on the energy separation between the ground state and the lowest excited state.
Publisher: IEEE
Date: 09-2011
Publisher: IEEE
Date: 09-2011
Publisher: Springer Science and Business Media LLC
Date: 29-11-2008
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2011
Publisher: IEEE
Date: 09-2011
Publisher: American Chemical Society (ACS)
Date: 31-07-2019
Publisher: IEEE
Date: 09-2010
Publisher: IEEE
Date: 11-2009
Publisher: Elsevier BV
Date: 06-2009
Publisher: SPIE
Date: 2012
DOI: 10.1117/12.909423
Publisher: IEEE
Date: 09-2010
Publisher: Wiley
Date: 02-06-2008
Publisher: Springer International Publishing
Date: 2018
Publisher: IEEE
Date: 10-2008
Publisher: IEEE
Date: 09-2013
Publisher: ACM
Date: 16-05-2016
Publisher: Elsevier BV
Date: 10-2009
Publisher: InTech
Date: 13-03-2017
DOI: 10.5772/67625
Publisher: AIP Publishing
Date: 13-07-2016
DOI: 10.1063/1.4955422
Abstract: A single electron dynamic memory is designed based on the non-equilibrium dynamics of charge states in electrostatically defined metallic quantum dots. Using the orthodox theory for computing the transfer rates and a master equation, we model the dynamical response of devices consisting of a charge sensor coupled to either a single and or a double quantum dot subjected to a pulsed gate voltage. We show that transition rates between charge states in metallic quantum dots are characterized by an asymmetry that can be controlled by the gate voltage. This effect is more pronounced when the switching between charge states corresponds to a Markovian process involving electron transport through a chain of several quantum dots. By simulating the dynamics of electron transport we demonstrate that the quantum box operates as a finite-state machine that can be addressed by choosing suitable shapes and switching rates of the gate pulses. We further show that writing times in the ns range and retention memory times six orders of magnitude longer, in the ms range, can be achieved on the double quantum dot system using experimentally feasible parameters, thereby demonstrating that the device can operate as a dynamic single electron memory.
Publisher: SPIE
Date: 08-09-2011
DOI: 10.1117/12.895440
Publisher: IEEE
Date: 06-2006
Publisher: IEEE
Date: 09-2016
Publisher: IEEE
Date: 06-2007
Publisher: IEEE
Date: 06-2007
Publisher: SPIE
Date: 21-04-2006
DOI: 10.1117/12.660923
Publisher: AIP Publishing
Date: 28-10-2014
DOI: 10.1063/1.4900995
Abstract: A methodology is proposed for designing a low-energy consuming ternary-valued full adder based on a quantum dot (QD) electrostatically coupled with a single electron transistor operating as a charge sensor. The methodology is based on design optimization: the values of the physical parameters of the system required for implementing the logic operations are optimized using a multiobjective genetic algorithm. The searching space is determined by elements of the capacitance matrix describing the electrostatic couplings in the entire device. The objective functions are defined as the maximal absolute error over actual device logic outputs relative to the ideal truth tables for the sum and the carry-out in base 3. The logic units are implemented on the same device: a single dual-gate quantum dot and a charge sensor. Their physical parameters are optimized to compute either the sum or the carry out outputs and are compatible with current experimental capabilities. The outputs are encoded in the value of the electric current passing through the charge sensor, while the logic inputs are supplied by the voltage levels on the two gate electrodes attached to the QD. The complex logic ternary operations are directly implemented on an extremely simple device, characterized by small sizes and low-energy consumption compared to devices based on switching single-electron transistors. The design methodology is general and provides a rational approach for realizing non-switching logic operations on QD devices.
Publisher: IEEE
Date: 06-2014
Publisher: American Physical Society (APS)
Date: 02-11-2015
Publisher: Springer Netherlands
Date: 12-09-2016
Publisher: IEEE
Date: 06-2014
Publisher: IEEE
Date: 06-2007
Publisher: InTech
Date: 04-2010
DOI: 10.5772/8566
Publisher: IEEE
Date: 09-2008
Publisher: IEEE
Date: 06-2007
Publisher: AIP Publishing LLC
Date: 2014
DOI: 10.1063/1.4878296
Publisher: IEEE
Date: 06-2006
Publisher: American Physical Society (APS)
Date: 05-2017
Publisher: Wiley
Date: 19-08-2022
Abstract: Hybrid inorganic–organic semiconductor (HIOS) interfaces are of interest for new photovoltaic devices operating above the Shockley–Queisser limit. Predicting energy band alignment at the interfaces is crucial for their design, but represents a challenging problem due to the large scales of the system, the energy precision required and a wide range of physical phenomena that occur at the interface. To tackle this problem, many‐body perturbation theory in the non‐self‐consistent GW approximation, orbital relaxation corrections for organic semiconductors, and line‐up potential method for inorganic semiconductors which allows for tractable and accurate computing of energy band alignment in crystalline van‐der‐Waals hybrid inorganic–organic semiconductor interfaces are used. In this work, crystalline tetracene physisorbed on the clean hydrogen‐passivated 1 × 2 reconstructed (100) silicon surface is studied. Using this computational approach, it is found that the energy band alignment is determined by an interplay of the mutual dynamic dielectric screening of two materials and the formation of a dipole layer due to a weak hybridization of atomic/molecular orbitals at the interface. The significant role of the exchange‐correlation effects in predicting band offsets for the hybrid inorganic–organic semiconductor interfaces is also emphasized.
Publisher: Wiley
Date: 11-12-2014
Publisher: IEEE
Date: 09-2010
Publisher: IOP Publishing
Date: 15-07-2014
Publisher: Elsevier BV
Date: 02-2021
Publisher: IEEE
Date: 09-2010
Publisher: Elsevier BV
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 06-11-2020
DOI: 10.1038/S41524-020-00429-W
Abstract: Organic photovoltaic (OPV) materials are promising candidates for cheap, printable solar cells. However, there are a very large number of potential donors and acceptors, making selection of the best materials difficult. Here, we show that machine-learning approaches can leverage computationally expensive DFT calculations to estimate important OPV materials properties quickly and accurately. We generate quantitative relationships between simple and interpretable chemical signature and one-hot descriptors and OPV power conversion efficiency (PCE), open circuit potential ( V oc ), short circuit density ( J sc ), highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, and the HOMO–LUMO gap. The most robust and predictive models could predict PCE (computed by DFT) with a standard error of ±0.5 for percentage PCE for both the training and test set. This model is useful for pre-screening potential donor and acceptor materials for OPV applications, accelerating design of these devices for green energy applications.
Location: Ukraine
No related grants have been discovered for Mykhailo Klymenko.