Pub Date : 2015-10-26DOI: 10.1109/IWCE.2015.7301950
Protik Das, G. Yin, S. Sylvia, Khairul Alamt, D. Wickramaratne, R. Lake
Mexican hat shaped dispersions are relatively common in few-layered two-dimensional materials. In one to four monolayers of the group-ill chalcogenides (GaS, GaSe, InS, InSe) the valence band undergoes a band inversion from parabolic to a Mexican hat dispersion [1]. This Mexican hat dispersion results in a singularity in the density of states at the band edge. This enhances the thermo electric properties, however the effect on field effect transistor performance has not yet been investigated. To evaluate the impact of this ring shaped disperision on FET performance, we use a top of the barrier FET model. The physical gate length, effective oxide thickness and power supply voltage for the simulated devices are 12.8 nm, 0.68nm, and 0.3V respectively, following the low-voltage parameters described by Nikonov and Young [2]. The simulated device is shown in Fig. 1. To model the electrostatic potential along the channel of the device we solve a 2-D Poisson equation over the simulation domain. The density of states and density of modes calculated from the Mexican hat dispersion described in Ref. [I] are shown in Figs. 2 and 3, respectively. The density of modes is used as input for the current calculation. The performance characteristics of the devices are benchmarked using the 15nm node low- voltage criteria defined by Nikonov and Young [2] and compared to other devices.
{"title":"The impact of the ring shaped valence band in few-layer iii-vi materials on fet operation","authors":"Protik Das, G. Yin, S. Sylvia, Khairul Alamt, D. Wickramaratne, R. Lake","doi":"10.1109/IWCE.2015.7301950","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301950","url":null,"abstract":"Mexican hat shaped dispersions are relatively common in few-layered two-dimensional materials. In one to four monolayers of the group-ill chalcogenides (GaS, GaSe, InS, InSe) the valence band undergoes a band inversion from parabolic to a Mexican hat dispersion [1]. This Mexican hat dispersion results in a singularity in the density of states at the band edge. This enhances the thermo electric properties, however the effect on field effect transistor performance has not yet been investigated. To evaluate the impact of this ring shaped disperision on FET performance, we use a top of the barrier FET model. The physical gate length, effective oxide thickness and power supply voltage for the simulated devices are 12.8 nm, 0.68nm, and 0.3V respectively, following the low-voltage parameters described by Nikonov and Young [2]. The simulated device is shown in Fig. 1. To model the electrostatic potential along the channel of the device we solve a 2-D Poisson equation over the simulation domain. The density of states and density of modes calculated from the Mexican hat dispersion described in Ref. [I] are shown in Figs. 2 and 3, respectively. The density of modes is used as input for the current calculation. The performance characteristics of the devices are benchmarked using the 15nm node low- voltage criteria defined by Nikonov and Young [2] and compared to other devices.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125032578","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 : 2015-10-26DOI: 10.1109/IWCE.2015.7301939
M. Bescond, N. Cavassilas, S. Berrada, M. Lannoo, H. Carrillo-Nuñez
In this work we investigate the dependence of electron-phonon scattering in single dopant-based nanowire transistor with respect to temperature and dimensions. We use a 3D real-space non-equilibrium Green's function (NEGF) approach where electron-phonon scattering is treated within the selfconsistent Born approximation (SCBA) through self-energies. We also use an analytic model to extend the validity of the acoustic phonon self-energy at low temperatures. Based on this model our simulations show the presence of a current hysteresis when reducing the temperature down to 150 K. The influence of channel length and nanowire cross-section on the dopant level contribution to the current is also discussed.
{"title":"Phonon interactions in single-dopant-based transistors: temperature and size dependence","authors":"M. Bescond, N. Cavassilas, S. Berrada, M. Lannoo, H. Carrillo-Nuñez","doi":"10.1109/IWCE.2015.7301939","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301939","url":null,"abstract":"In this work we investigate the dependence of electron-phonon scattering in single dopant-based nanowire transistor with respect to temperature and dimensions. We use a 3D real-space non-equilibrium Green's function (NEGF) approach where electron-phonon scattering is treated within the selfconsistent Born approximation (SCBA) through self-energies. We also use an analytic model to extend the validity of the acoustic phonon self-energy at low temperatures. Based on this model our simulations show the presence of a current hysteresis when reducing the temperature down to 150 K. The influence of channel length and nanowire cross-section on the dopant level contribution to the current is also discussed.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126021867","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 : 2015-10-26DOI: 10.1109/IWCE.2015.7301945
Shripriya Poduri, M. Choi, M. Dutta, M. Stroscio
ZnO nanostructures have generated interest for a wide range of applications due to their unique optical and electrical properties. Especially, the spontaneous polarization in the ZnO nanostructure which produces a permanent strong static electric field that can be applied to many studies. Also, their strong polarizability makes them potential candidates for many applications such as ion channel modulation, photodetector and LEDs in UV range. In this paper, the plasmonic enhancement of the induced electric field produced from ZnO nanostructures is computed by numerical analysis.
{"title":"Numerical analysis of electric field enhancement in ZnO film with plasmonic au quantum dots","authors":"Shripriya Poduri, M. Choi, M. Dutta, M. Stroscio","doi":"10.1109/IWCE.2015.7301945","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301945","url":null,"abstract":"ZnO nanostructures have generated interest for a wide range of applications due to their unique optical and electrical properties. Especially, the spontaneous polarization in the ZnO nanostructure which produces a permanent strong static electric field that can be applied to many studies. Also, their strong polarizability makes them potential candidates for many applications such as ion channel modulation, photodetector and LEDs in UV range. In this paper, the plasmonic enhancement of the induced electric field produced from ZnO nanostructures is computed by numerical analysis.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115296568","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 : 2015-10-19DOI: 10.1109/IWCE.2015.7301948
X. Oriols, Zhen Zhan, E. Colomés, D. Marian
An effective single-particle Schrodinger equation to include dissipation into quantum devices is presented. This effective equation is fully understood in the context of Bohmian mechanics, a theory of particles and waves, where it is possible to define unambiguously the wave function of a subsystem, the so-called conditional wave function. In particular the change in energy and momentum of an electron when interacting with a phonon is presented, both theoretically and numerically. This work is a first step to include dissipation into the fully-quantum simulator BITLLES.
{"title":"Dissipative quantum transport using one-particle time-dependent (conditional) wave functions","authors":"X. Oriols, Zhen Zhan, E. Colomés, D. Marian","doi":"10.1109/IWCE.2015.7301948","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301948","url":null,"abstract":"An effective single-particle Schrodinger equation to include dissipation into quantum devices is presented. This effective equation is fully understood in the context of Bohmian mechanics, a theory of particles and waves, where it is possible to define unambiguously the wave function of a subsystem, the so-called conditional wave function. In particular the change in energy and momentum of an electron when interacting with a phonon is presented, both theoretically and numerically. This work is a first step to include dissipation into the fully-quantum simulator BITLLES.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131851771","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 : 2015-10-19DOI: 10.1109/IWCE.2015.7301969
Yi Lan, Chenjie Tang, J. Shi, M. Dutta, M. Stroscio
A reduced signal-to-noise reduced photodetector has been designed using single-and double-quantum well structures as well as phonon assisted transitions. To increase electron carriers, delta-doping is used in the first single well. In this contribution, the energy levels of the single-well-double-well structure are prescribed by determining the energy spectrum for the interface phonon potentials and their dispersion curves. And delta-doping at middle of well is shown to have advantage in obtaining higher absorption coefficient than uniform doping.
{"title":"Phononic properties for enhanced signal-to-noise photodetector","authors":"Yi Lan, Chenjie Tang, J. Shi, M. Dutta, M. Stroscio","doi":"10.1109/IWCE.2015.7301969","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301969","url":null,"abstract":"A reduced signal-to-noise reduced photodetector has been designed using single-and double-quantum well structures as well as phonon assisted transitions. To increase electron carriers, delta-doping is used in the first single well. In this contribution, the energy levels of the single-well-double-well structure are prescribed by determining the energy spectrum for the interface phonon potentials and their dispersion curves. And delta-doping at middle of well is shown to have advantage in obtaining higher absorption coefficient than uniform doping.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116421244","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 : 2015-09-30DOI: 10.1109/IWCE.2015.7301987
M. V. D. Put, W. Vandenberghe, Bart Sor'ee, Wim Magnus, Massimo Fischetti
The tunneling current between two crossed graphene ribbons is described invoking the empirical pseudopotential approximation and the Bardeen transfer Hamiltonian method. Results indicate that the density of states is the most important factor determining the tunneling current between small (~nm) ribbons. The quasi-one dimensional nature of graphene nanoribbons is shown to result in resonant tunneling.
{"title":"Modeling of inter-ribbon tunneling in graphene","authors":"M. V. D. Put, W. Vandenberghe, Bart Sor'ee, Wim Magnus, Massimo Fischetti","doi":"10.1109/IWCE.2015.7301987","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301987","url":null,"abstract":"The tunneling current between two crossed graphene ribbons is described invoking the empirical pseudopotential approximation and the Bardeen transfer Hamiltonian method. Results indicate that the density of states is the most important factor determining the tunneling current between small (~nm) ribbons. The quasi-one dimensional nature of graphene nanoribbons is shown to result in resonant tunneling.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117046763","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 : 2015-09-29DOI: 10.1109/IWCE.2015.7301975
K. Moors, B. Sorée, W. Magnus
Ando's surface roughness model is applied to metallic nanowires and extended beyond small roughness size and infinite barrier limit approximations for the wavefunction overlaps, such as the Prange-Nee approximation. Accurate and fast simulations can still be performed without invoking these overlap approximations by averaging over roughness profiles using finite domain distribution functions to obtain an analytic solution for the scattering rates. The simulations indicate that overlap approximations, while predicting a resistivity that agrees more or less with our novel approach, poorly estimate the underlying scattering rates. All methods show that a momentum gap between left- and right-moving electrons at the Fermi level, surpassing a critical momentum gap, gives rise to a substantial decrease in resistivity.
{"title":"Analytic solution of ando’s surface roughness model with finite domain distribution functions","authors":"K. Moors, B. Sorée, W. Magnus","doi":"10.1109/IWCE.2015.7301975","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301975","url":null,"abstract":"Ando's surface roughness model is applied to metallic nanowires and extended beyond small roughness size and infinite barrier limit approximations for the wavefunction overlaps, such as the Prange-Nee approximation. Accurate and fast simulations can still be performed without invoking these overlap approximations by averaging over roughness profiles using finite domain distribution functions to obtain an analytic solution for the scattering rates. The simulations indicate that overlap approximations, while predicting a resistivity that agrees more or less with our novel approach, poorly estimate the underlying scattering rates. All methods show that a momentum gap between left- and right-moving electrons at the Fermi level, surpassing a critical momentum gap, gives rise to a substantial decrease in resistivity.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121263863","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 : 2015-09-17DOI: 10.1109/IWCE.2015.7301979
Á. Papp, G. Csaba, W. Porod
We investigate the use of microstrip lines for short-wavelength spin-wave generation in magnetic thin films. We use micromagnetic and electromagnetic simulations to estimate the generated wave amplitudes for different geometries and at different frequencies. Our results suggest that in applications where coherent wavefronts need to be generated a microstrip line might also be used instead of more complicated devices (e.g. spin-torque oscillators) with comparable efficiency.
{"title":"Short-wavelength spin-wave generation by a microstrip line","authors":"Á. Papp, G. Csaba, W. Porod","doi":"10.1109/IWCE.2015.7301979","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301979","url":null,"abstract":"We investigate the use of microstrip lines for short-wavelength spin-wave generation in magnetic thin films. We use micromagnetic and electromagnetic simulations to estimate the generated wave amplitudes for different geometries and at different frequencies. Our results suggest that in applications where coherent wavefronts need to be generated a microstrip line might also be used instead of more complicated devices (e.g. spin-torque oscillators) with comparable efficiency.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121285492","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 : 2015-09-04DOI: 10.1109/IWCE.2015.7301962
D. Guo, D. Brinkman, T. Fang, R. Akis, I. Sankin, D. Vasileska, C. Ringhofer
In this work, we report on development of one-dimensional (1D) finite-difference and two-dimensional (2D) finite-element diffusion-reaction simulators to investigate mechanisms behind Cu-related metastabilities observed in CdTe solar cells [1]. The evolution of CdTe solar cells performance has been studied as a function of stress time in response to the evolution of associated acceptor and donor states. To achieve such capability, the simulators solve reaction-diffusion equations for the defect states in time-space domain self-consistently with the free carrier transport. Results of 1-D and 2-D simulations have been compared to verify the accuracy of solutions.
{"title":"Diffusion-reaction modeling of Cu migration in CdTe solar devices","authors":"D. Guo, D. Brinkman, T. Fang, R. Akis, I. Sankin, D. Vasileska, C. Ringhofer","doi":"10.1109/IWCE.2015.7301962","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301962","url":null,"abstract":"In this work, we report on development of one-dimensional (1D) finite-difference and two-dimensional (2D) finite-element diffusion-reaction simulators to investigate mechanisms behind Cu-related metastabilities observed in CdTe solar cells [1]. The evolution of CdTe solar cells performance has been studied as a function of stress time in response to the evolution of associated acceptor and donor states. To achieve such capability, the simulators solve reaction-diffusion equations for the defect states in time-space domain self-consistently with the free carrier transport. Results of 1-D and 2-D simulations have been compared to verify the accuracy of solutions.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"6 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113981496","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 : 2015-09-01DOI: 10.1109/IWCE.2015.7301959
K. Fukuda, Y. Morita, T. Mori, W. Mizubayashi, M. Masahara, T. Yasuda, S. Migita, H. Ota
Tunnel FETs with vertical tunnel paths are fabricated and successfully modeled by the nonlocal band to band tunneling model. Although enhancement of ON currents are obtained by longer source gate overlap lengths, the increase of the ON current is less than proportional to the overlap lengths, because of non-uniformity of the band to band tunneling generation rates. The behavior of this type of tunnel FETs is precisely explained by the device simulation model. The key point is the peak generation rates at the source edge.
{"title":"Modeling of parallel electric field tunnel FETs","authors":"K. Fukuda, Y. Morita, T. Mori, W. Mizubayashi, M. Masahara, T. Yasuda, S. Migita, H. Ota","doi":"10.1109/IWCE.2015.7301959","DOIUrl":"https://doi.org/10.1109/IWCE.2015.7301959","url":null,"abstract":"Tunnel FETs with vertical tunnel paths are fabricated and successfully modeled by the nonlocal band to band tunneling model. Although enhancement of ON currents are obtained by longer source gate overlap lengths, the increase of the ON current is less than proportional to the overlap lengths, because of non-uniformity of the band to band tunneling generation rates. The behavior of this type of tunnel FETs is precisely explained by the device simulation model. The key point is the peak generation rates at the source edge.","PeriodicalId":165023,"journal":{"name":"2015 International Workshop on Computational Electronics (IWCE)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128734788","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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