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Title: Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures

Abstract

This final report describes the work done by Jack Dongarra (University Distinguished Professor) and Stanimire Tomov (Research Scientist) related to the DOE project entitled Predicting the Electronic Properties of 3D, Million-Atom Semiconductor Nanostructure Architectures. In this project we addressed the mathematical methodology required to calculate the electronic and transport properties of large nanostructures with comparable accuracy and reliability to that of current ab initio methods. This capability is critical for further developing the field, yet it is missing in all the existing computational methods. Additionally, quantitative comparisons with experiments are often needed for a qualitative understanding of the physics, and for guiding the design of new nanostructures. We focused on the mathematical challenges of the project, in particular on solvers and preconditioners for large scale eigenvalue problems that occur in the computation of electronic states of large nanosystems. Usually, the states of interest lie in the interior of the spectrum and their computation poses great difficulties for existing algorithms. The electronic properties of a semiconductor nanostructure architecture can be predicted/determined by computing its band structure. Of particular importance are the 'band edge states' (electronic states near the energy gap) which can be computed from a properly defined interior eigenvalue problem.more » Our primary mathematics and computational challenge here has been to develop an efficient solution methodology for finding these interior states for very large systems. Our work has produced excellent results in terms of developing both new and extending current state-of-the-art techniques.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org.:
USDOE SC Office of Advanced Scientific Computing Research (SC-21); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1036499
Report Number(s):
DOE/ER25584-5
TRN: US201208%%869
DOE Contract Number:
FG02-03ER25584
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ACCURACY; ALGORITHMS; ARCHITECTURE; DESIGN; EIGENVALUES; ENERGY GAP; NANOSTRUCTURES; PHYSICS; RELIABILITY; TRANSPORT; computational nano-technology; electronic structure; preconditioned conjugate gradients; bulk band; quantum dots; parallel eigenvalue solvers; block method

Citation Formats

Jack Dongarra, and Stanimire Tomov. Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures. United States: N. p., 2012. Web. doi:10.2172/1036499.
Jack Dongarra, & Stanimire Tomov. Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures. United States. doi:10.2172/1036499.
Jack Dongarra, and Stanimire Tomov. 2012. "Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures". United States. doi:10.2172/1036499. https://www.osti.gov/servlets/purl/1036499.
@article{osti_1036499,
title = {Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures},
author = {Jack Dongarra and Stanimire Tomov},
abstractNote = {This final report describes the work done by Jack Dongarra (University Distinguished Professor) and Stanimire Tomov (Research Scientist) related to the DOE project entitled Predicting the Electronic Properties of 3D, Million-Atom Semiconductor Nanostructure Architectures. In this project we addressed the mathematical methodology required to calculate the electronic and transport properties of large nanostructures with comparable accuracy and reliability to that of current ab initio methods. This capability is critical for further developing the field, yet it is missing in all the existing computational methods. Additionally, quantitative comparisons with experiments are often needed for a qualitative understanding of the physics, and for guiding the design of new nanostructures. We focused on the mathematical challenges of the project, in particular on solvers and preconditioners for large scale eigenvalue problems that occur in the computation of electronic states of large nanosystems. Usually, the states of interest lie in the interior of the spectrum and their computation poses great difficulties for existing algorithms. The electronic properties of a semiconductor nanostructure architecture can be predicted/determined by computing its band structure. Of particular importance are the 'band edge states' (electronic states near the energy gap) which can be computed from a properly defined interior eigenvalue problem. Our primary mathematics and computational challenge here has been to develop an efficient solution methodology for finding these interior states for very large systems. Our work has produced excellent results in terms of developing both new and extending current state-of-the-art techniques.},
doi = {10.2172/1036499},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2012,
month = 3
}

Technical Report:

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  • The performance of electronic circuits and systems in a radiation environment can be determined if the radiation induced component changes are known and if system performance as a function of component changes can be determined. The most economical way of determining alterations of system performance caused by radiation combines analysis with an experimental technique intended for laboratory use. The analytical method requires that the performance of the system be expressed mathematically in terms of component performance. These equations are then solved using component parameters appropriate to discrete radiation levels. This approach also can be used to determine the probability ofmore » system failure as a function of radiation exposure. The experimental technique involves measuring system performance after substituting radiation-degraded components into it. Although this latter technique only yields the radiation levels for zero and 100% probability of failure, it is a simple and powerful tool. Exposing a system to radiation in order to determine failure levels or failure probabilities is not practical because the large variations normally encountered in semiconductor device parameters may cause failure to occur over a large range of radiation exposure levels. Therefore, a few observations on a specific system are not a reasonable basis for predicting radiation performance of similar systems. (auth)« less
  • Increased use of semiconductor devices in nuclear environments necessitates an understanding of performance changes due to radiation. Analytical methods involving equations describing component and circuit performance as a function of radiation and experimental methods based either on observance of the performance of pre-irradiated components in a circuit or on actual irradiation of the circuit can determine failure levels and probabilities. Advantages and disadvantages of the methods are discussed as are the actual effects and mechanisms of radiation damage. Estimation of system failure levels, signlficance of surface effects, and design techniques for minimizing radiation effects are also treated. Variations of initialmore » outputs of components make prediction of failures more difficult and demand high quality control. (D.C.W.)« less
  • Scintillators, materials that emit short flashes of light in response to ionizing radiation, are used to detect high-energy radiation (charged particles, x-rays, or gamma rays) from various sources. The authors are modeling the properties of these materials for the purpose of guiding the synthesis of new scintillators with improved detection capabilities. Their calculational tools include methods based on the local density approximation (LDA), such as pseudopotential and all-electron methods, and quasiparticle approaches. They have used their all-electron LDA method to calculate the atomic structure of barium fluoride and lead fluoride, both of which can exist in one of two phasesmore » (either cubic or orthorhombic) at low pressures. Their calculations have accurately reproduced the experimentally observed structural properties of these materials. They have also provided insight into their electronic properties. Ultimately, they want to calculate the energies of defect excitations. This is of great practical interest because the optical properties of a material can be tailored by introducing defect levels inside the fundamental band gap.« less
  • The objective was to analyze the electronic properties of different semiconductor interfaces. The Wannier function formalism has been applied to the GaAs-AlAs (111) and (100) heterojunctions and superlattices. Ionic relaxations, band discontinuities and interface states have been obtained. Abrupt Si-metal interfaces and Si-interlayer-metal junctions have been analyzed by means of a self-consistent tight-binding approach. The barrier height has been obtained by calculating the interface density of states and the neutral level of the junction. Our results show that the barrier height is mainly determined by the coupling between the semiconductor and the last layer just sitting on top of themore » same semiconductor.« less
  • This proposal was mainly concerned with the theoretical study of semiconductor compounds, alloys, and superlattices of interest for photovoltaic applications. In the last year (1991) a study was devoted to metal/graphite bonding in relation to use of graphite fiber reinforcement of Cu for high thermal conductivity applications. The main research topics addressed during the full period of the grant are briefly described: studies of the In-Ga-As ternary system; band-offsets at common anion and InAs/GaSb/AlSb heterojunctions; alloy theory (cluster variation method); and Cu/graphite bonding. Most of the work was described more extensively in previous yearly reports and renewal applications and inmore » publications. A list of publications resulting directly from this grant or from other grants but related to this work and of conference presentations is given at the end.« less