Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091095
S. E. Laux
Complex bands are computed for Si using a spds* atomistic tight binding Hamiltonian with spin orbit splitting for both bulk and confined structures. Representative band structures are shown. The bulk Si calculations imply that band-toband tunneling current should be less in the [1 0 0] direction compared to either [1 1 0] or [1 1 1] directions, which is qualitatively consistent with experiment.
{"title":"Computation of Complex Band Structures in Bulk and Confined Structures","authors":"S. E. Laux","doi":"10.1109/IWCE.2009.5091095","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091095","url":null,"abstract":"Complex bands are computed for Si using a spds* atomistic tight binding Hamiltonian with spin orbit splitting for both bulk and confined structures. Representative band structures are shown. The bulk Si calculations imply that band-toband tunneling current should be less in the [1 0 0] direction compared to either [1 1 0] or [1 1 1] directions, which is qualitatively consistent with experiment.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114918011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091103
N. Dehdashti, A. Afzalian, C. Lee, R. Yan, G. Fagas, J. Colinge
We have investigated the effect of symmetric geometrical constrictions on the device characteristics of ultrathin silicon-on-insulator (SOI) nanowire with Trigate structure by means of the full real-space three dimensional Non-equilibrium Greens’s Function (NEGF) method. In this study, geometrical constrictions are introduced as energy barriers near the source and the drain junctions and their strength is modulated by the potential height and the geometry. Interestingly, even at room temperature the drain current in the device shows oscillations as a function of the applied gate voltage. This can be traced to the development of transmission resonances as the channel is additionally confined along the current direction.
{"title":"Device Characteristics of Trigate-FET with Barrier Constrictions in the Channel","authors":"N. Dehdashti, A. Afzalian, C. Lee, R. Yan, G. Fagas, J. Colinge","doi":"10.1109/IWCE.2009.5091103","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091103","url":null,"abstract":"We have investigated the effect of symmetric geometrical constrictions on the device characteristics of ultrathin silicon-on-insulator (SOI) nanowire with Trigate structure by means of the full real-space three dimensional Non-equilibrium Greens’s Function (NEGF) method. In this study, geometrical constrictions are introduced as energy barriers near the source and the drain junctions and their strength is modulated by the potential height and the geometry. Interestingly, even at room temperature the drain current in the device shows oscillations as a function of the applied gate voltage. This can be traced to the development of transmission resonances as the channel is additionally confined along the current direction.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122728372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091159
M. van Schilfgaarde, T. Kotani
Most materials properties of interest are governed by the behavior of the electrons. They directly participate in almost all electrical, magnetic and optical properties, and are responsible for the forces acting on nuclei, which affects structural and mechanical response. In this talk, I will briefly outline the present status of ab initio electronic structure theory, that is systematic methods to obtain effective one-body Hamiltonians which govern the electronic equations of motion, starting from first principles. I will present a newly developed quasiparticle self-consistent GW (QSGW) approximation, and show that it can generate very accurate one-body Hamiltonians, and is therefore a suitable engine for build device simulators from first principles.
{"title":"Towards ab initio Device Design: The Quasiparticle Self-Consistent GW Approximation","authors":"M. van Schilfgaarde, T. Kotani","doi":"10.1109/IWCE.2009.5091159","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091159","url":null,"abstract":"Most materials properties of interest are governed by the behavior of the electrons. They directly participate in almost all electrical, magnetic and optical properties, and are responsible for the forces acting on nuclei, which affects structural and mechanical response. In this talk, I will briefly outline the present status of ab initio electronic structure theory, that is systematic methods to obtain effective one-body Hamiltonians which govern the electronic equations of motion, starting from first principles. I will present a newly developed quasiparticle self-consistent GW (QSGW) approximation, and show that it can generate very accurate one-body Hamiltonians, and is therefore a suitable engine for build device simulators from first principles.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116825353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091134
A. Paul, S. Mehrotra, Gerhard Klimeck, M. Luisier
This work focuses on the determination of the valid device domain for the use of the Top of the barrier (ToB) model to simulate quantum transport in nanowire MOSFETs in the ballistic regime. The presence of a proper Source/Drain barrier in the device is an important criterion for the applicability of the model. Long channel devices can be accurately modeled under low and high drain bias with DIBL adjustment. Keywords-component; nanowires; top of the barrier; MOSFET; ballistic transport model; DIBL; tunneling current; top-of-the- barrier; subthreshold- slope; Tight-Binding;Short channel effects .
{"title":"On the Validity of the Top of the Barrier Quantum Transport Model for Ballistic Nanowire MOSFETs","authors":"A. Paul, S. Mehrotra, Gerhard Klimeck, M. Luisier","doi":"10.1109/IWCE.2009.5091134","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091134","url":null,"abstract":"This work focuses on the determination of the valid device domain for the use of the Top of the barrier (ToB) model to simulate quantum transport in nanowire MOSFETs in the ballistic regime. The presence of a proper Source/Drain barrier in the device is an important criterion for the applicability of the model. Long channel devices can be accurately modeled under low and high drain bias with DIBL adjustment. Keywords-component; nanowires; top of the barrier; MOSFET; ballistic transport model; DIBL; tunneling current; top-of-the- barrier; subthreshold- slope; Tight-Binding;Short channel effects .","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123900818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091153
G. Penazzi, A. Pecchia, F. Sacconi, M. Auf der Maur, M. Povolotskyi, G. Romano, A. Di Carlo
Calculations of optoelectronic properties of a GaN quantum dot embedded in an AlGaN nanocolumn are presented, using the TiberCAD simulator. The calculations emphasize the role of the growth direction in determining the quantum efficiency of such light emitting devices. Multiband kldrp is used, with corrections from drift diffusion and strain calculations. Results are discussed using an empirical tight binding method, with the same macroscopic corrections as for kldrp, implemented in TiberCAD framework itself.
{"title":"Simulations of Optical Properties of a GaN Quantum Dot Embedded in a AlGaN Nanocolumn within a Mixed FEM/atomistic Method","authors":"G. Penazzi, A. Pecchia, F. Sacconi, M. Auf der Maur, M. Povolotskyi, G. Romano, A. Di Carlo","doi":"10.1109/IWCE.2009.5091153","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091153","url":null,"abstract":"Calculations of optoelectronic properties of a GaN quantum dot embedded in an AlGaN nanocolumn are presented, using the TiberCAD simulator. The calculations emphasize the role of the growth direction in determining the quantum efficiency of such light emitting devices. Multiband kldrp is used, with corrections from drift diffusion and strain calculations. Results are discussed using an empirical tight binding method, with the same macroscopic corrections as for kldrp, implemented in TiberCAD framework itself.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124009458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091130
P. Marconcini, G. Fiori, A. Ferretti, G. Iannaccone, M. Macucci
We have performed a numerical investigation of the effect of boron doping on the dispersion relations of armchair graphene nanoribbons, finding that it should reduce the strong variability of the energy gap predicted for atomic-scale fluctuations of the nanoribbon width. We also present the transport characteristics that we have obtained, within a self-consistent Non Equilibrium Green's Function (NEGF) simulation, for a field-effect transistor based on boron-doped graphene nanoribbons. As a consequence of doping, mobility, and thus the current through the device, are suppressed, but there seems to be a possibility to mitigate this adverse effect, by locating the dopants near the edges of the nanoribbon, their energetically favored position.
{"title":"Numerical Analysis of Transport Properties of Boron-Doped Graphene FETs","authors":"P. Marconcini, G. Fiori, A. Ferretti, G. Iannaccone, M. Macucci","doi":"10.1109/IWCE.2009.5091130","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091130","url":null,"abstract":"We have performed a numerical investigation of the effect of boron doping on the dispersion relations of armchair graphene nanoribbons, finding that it should reduce the strong variability of the energy gap predicted for atomic-scale fluctuations of the nanoribbon width. We also present the transport characteristics that we have obtained, within a self-consistent Non Equilibrium Green's Function (NEGF) simulation, for a field-effect transistor based on boron-doped graphene nanoribbons. As a consequence of doping, mobility, and thus the current through the device, are suppressed, but there seems to be a possibility to mitigate this adverse effect, by locating the dopants near the edges of the nanoribbon, their energetically favored position.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125576976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091151
Y. Sheng, Y.G. Xiao, Y. Zhou, Z. Q. Li, Z. Simon Li, Z. Li
Crystalline silicon solar cells with laser-fired contact (LFC) are simulated with Crosslight APSYS and CSUPREM. Different laser firing parameters lead to different LFC profiles and different cell performances. It is shown that the cell efficiency can be improved to a relatively stable value by increasing concentration of aluminum clusters, lasing time or laser spot diameter. The results are further explained quantitatively by dark current and qualitatively by built-in potential.
{"title":"Simulation on Crystalline Silicon Solar Cell with Laser-fired Contact (LFC)","authors":"Y. Sheng, Y.G. Xiao, Y. Zhou, Z. Q. Li, Z. Simon Li, Z. Li","doi":"10.1109/IWCE.2009.5091151","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091151","url":null,"abstract":"Crystalline silicon solar cells with laser-fired contact (LFC) are simulated with Crosslight APSYS and CSUPREM. Different laser firing parameters lead to different LFC profiles and different cell performances. It is shown that the cell efficiency can be improved to a relatively stable value by increasing concentration of aluminum clusters, lasing time or laser spot diameter. The results are further explained quantitatively by dark current and qualitatively by built-in potential.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130235200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091158
V. Sverdlov, O. Baumgartner, H. Kosina, S. Selberherr, F. Schanovsky, D. Esseni
A generalization of the “Linear Combination of Bulk Bands” method for the calculation of the electron and hole subband structure including strain and spin-orbit interaction is presented. Using the full band structure obtained numerically with the empirical pseudopotential method it is demonstrated that, contrary to the effective mass approximation, the unprimed subbands with the same quantum number in a (001) thin silicon film are not equivalent. It is shown that shear strain modifies the subband effective masses and introduces a large splitting between the unprimed subbands. The generalized method provides accurate subband dispersions for holes demonstrating a large potential for applications.
{"title":"The Linear Combination of Bulk Bands-Method for Electron and Hole Subband Calculations in Strained Silicon Films and Surface Layers","authors":"V. Sverdlov, O. Baumgartner, H. Kosina, S. Selberherr, F. Schanovsky, D. Esseni","doi":"10.1109/IWCE.2009.5091158","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091158","url":null,"abstract":"A generalization of the “Linear Combination of Bulk Bands” method for the calculation of the electron and hole subband structure including strain and spin-orbit interaction is presented. Using the full band structure obtained numerically with the empirical pseudopotential method it is demonstrated that, contrary to the effective mass approximation, the unprimed subbands with the same quantum number in a (001) thin silicon film are not equivalent. It is shown that shear strain modifies the subband effective masses and introduces a large splitting between the unprimed subbands. The generalized method provides accurate subband dispersions for holes demonstrating a large potential for applications.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134215823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091113
Jiseok Kim, M. Fischetti
The electronic band structure of relaxed and biaxially strained Si, Ge, III-V semiconductors (GaAs, GaSb, InAs, InSb, InP) and their alloys (In x Ga 1-x As, In x Ga 1-x Sb) on different interface orientations, (001), (110) and (111), is calculated using the nonlocal empirical pseudopotential method (EPM) with spin-orbit interaction using cubic spline interpolations of the atomic form factors. For III-V alloys, the virtual crystal approximation (VCA) is employed to calculate the band gap bowing parameters. Calculated results such as band gap (direct and indirect), band gap bowing parameters, and deformation potentials are fitted to the experimental data when available. Deformation potentials are determined using linear deformation potential theory when the small biaxial strain (in-plane) is present.
利用原子形状因子的三次样条插值，利用非局域经验赝势法(EPM)计算了不同界面取向(001)、(110)和(111)上的弛豫和双轴应变Si、Ge、III-V半导体(GaAs、GaSb、InAs、InSb、InP)及其合金(In x Ga 1-x As、In x Ga 1-x Sb)的电子能带结构。对于III-V合金，采用虚拟晶体近似(VCA)计算带隙弯曲参数。计算结果如带隙(直接和间接)，带隙弯曲参数和变形势拟合实验数据。当存在小的双轴应变(平面内)时，使用线性变形势理论确定变形势。
{"title":"Empirical Pseudopotential Calculation of Band Structure and Deformation Potentials of Biaxially Strained Semiconductors","authors":"Jiseok Kim, M. Fischetti","doi":"10.1109/IWCE.2009.5091113","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091113","url":null,"abstract":"The electronic band structure of relaxed and biaxially strained Si, Ge, III-V semiconductors (GaAs, GaSb, InAs, InSb, InP) and their alloys (In x Ga 1-x As, In x Ga 1-x Sb) on different interface orientations, (001), (110) and (111), is calculated using the nonlocal empirical pseudopotential method (EPM) with spin-orbit interaction using cubic spline interpolations of the atomic form factors. For III-V alloys, the virtual crystal approximation (VCA) is employed to calculate the band gap bowing parameters. Calculated results such as band gap (direct and indirect), band gap bowing parameters, and deformation potentials are fitted to the experimental data when available. Deformation potentials are determined using linear deformation potential theory when the small biaxial strain (in-plane) is present.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"548 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131818603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-05-27DOI: 10.1109/IWCE.2009.5091101
D. Querlioz, J. Saint-Martin, P. Dollfus
In this paper we discuss the effect of decoherence induced by electron-phonon scattering at room temperature in nanoscale devices where quantum transport effects play an important role as the RTD and the nano-MOSFET. The analysis is carried out from results of quantum Monte Carlo simulation based on the Wigner's function formalism. It puts forward the scattering-induced localization of electrons and the transition between the quantum and the semi-classical transport regimes in RTD. At last, the backscattering theory in MOSFET is investigated in the context of decohrence.
{"title":"Decoherence Due to Electron-Phonon Scattering in Semiconductor Nanodevices","authors":"D. Querlioz, J. Saint-Martin, P. Dollfus","doi":"10.1109/IWCE.2009.5091101","DOIUrl":"https://doi.org/10.1109/IWCE.2009.5091101","url":null,"abstract":"In this paper we discuss the effect of decoherence induced by electron-phonon scattering at room temperature in nanoscale devices where quantum transport effects play an important role as the RTD and the nano-MOSFET. The analysis is carried out from results of quantum Monte Carlo simulation based on the Wigner's function formalism. It puts forward the scattering-induced localization of electrons and the transition between the quantum and the semi-classical transport regimes in RTD. At last, the backscattering theory in MOSFET is investigated in the context of decohrence.","PeriodicalId":443119,"journal":{"name":"2009 13th International Workshop on Computational Electronics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115638961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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