1 / 1

Task 6.1: Atomistic Simulation of Graphene Transistors

Task 6.1: Atomistic Simulation of Graphene Transistors. G. Bulk. S. D. 1 S. Kim, 2 M. Luisier, 3 T. B. Boykin, 1 J. Geng, 1 J. Fonseca, 1 G. Klimeck 1 Purdue University, 2 ETH Zürich, 3 University of Alabama in Huntsville. Efield. G. Graphene. S. D. AGNR 13.

stash
Télécharger la présentation

Task 6.1: Atomistic Simulation of Graphene Transistors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Task 6.1: Atomistic Simulation of Graphene Transistors G Bulk S D 1S. Kim, 2M. Luisier, 3T. B. Boykin, 1J. Geng, 1J. Fonseca, 1G. Klimeck 1Purdue University, 2ETH Zürich, 3University of Alabama in Huntsville Efield G Graphene S D AGNR 13 pz vs p/d Tight-binding Model Why Graphene? Graphene Nanoribbon Transistors AGNR 12 Graphene Bandstructure Graphene Nanoribbon Confinement Experimental realization Simulation (pz-TB) http://en.wikipedia.org/wiki/Graphene DIBL suppressed NEMO5 Akturk, JAP2008 Shishir, JPCM2009 OMEN: Boykin, et al., JAP2011 Wang, PRL2008 • p/d model necessary to reproduce the asymmetry at Dirac point Betti, ITED2011 Problem: No bandgap Frank schwierz, Nature Nano. 2010 • Experimental realization of GNRFETs • Edge roughness is very important at small width (w<2.5 nm) OMEN- https://engineering.purdue.edu/gekcogrp/software-projects/omen/ NEMO5- https://engineering.purdue.edu/gekcogrp/software-projects/nemo5/ Excellent high field transport/mobility pz vs p/d Tight-binding Model Mobility vs Experiment Edge Roughness and Hydrogen Passivation Roughness Vd Edge roughness n~ 0.95x1013/cm2 S D Hydro. Pass. C Id H Vd Hydrogen passivation roughness Experiment: Wang, PRL2008 D S Edge roughness Id • Atomistic study of edge roughness and hydrogen passivation roughness • Reproducing experimentally possible situation p/d better match with DFT pz-wrong bandgap 2 • Edge roughness limited mobility much smaller than hydrogen passivation limited mobllity pz-wrong off-current OMEN: Boykin, et al., JAP2011 Bandgap vs. Neckwidth Bandstructure Effects Graphene Nanomesh Graphene 33 nm w = 26 nm w = 11 nm w = 19 nm Edge Roughness Hydrogen Passivation Roughness 138x138 uc P=50 % C H C Zero bandgap Bandgap Bandgap Bandgap H AGNR-12 AGNR-13 Second subband 33 nm First subband NEMO5 Simulation Structure Ef Ef Flat bands are ignored in bandgap calculation (crieterion: dE/dk<0.53 eV ) w Experiment: Liang et al., NanoLett 2010 Bandgap Comparison with Experiment Effects of Edge States Conclusion / Future Work • Bandgap uncertainty due to edge roughness • Electron Localization • Conclusion • Importance of p/d model in graphene modeling • Significant effects of edge roughness on electron mobility via bandstructure modification in GNRs • Relatively less effective hydrogen passivation effects in GNRs • GNM bandgap prediction through NEMO5 simulation • Future Work • GNR width dependent mobility and ON/OFF-current • GNM effects of edge roughness, different shape of holes • GNM transmission/mobility calculation • GNR, GNM self-consistent transport simulation D=24 nm w=9.7 nm Edge states Eg Γ Γ • Trend of experimental data captured • Overestimation of bangap at a small neck width < 10 nm Edge states criterion: dE/dk<0.53 eV

More Related