-- Preface ix -- Acknowledgements xi -- 1 Emerging Technologies 1 -- 1.1 Moore's Law and the Power Crisis 1 -- 1.2 Novel Device Architectures 2 -- 1.3 High Mobility Channel Materials 5 -- 1.4 Two?-Dimensional (2?-D) Materials 7 -- 1.5 Atomistic Modeling 8 -- 2 First?-principles calculations for Si nanostructures 12 -- 2.1 Band structure calculations 12 -- 2.1.1 Si ultrathin?-body structures 12 -- 2.1.2 Si nanowires 17 -- 2.1.3 Strain effects on band structures: From bulk to nanowire 20 -- 2.2 Tunneling current calculations through Si/SiO2/Si structures 31 -- 2.2.1 Atomic models of Si (001)/SiO2 /Si (001) structures 32 -- 2.2.2 Current?-voltage characteristics 33 -- 2.2.3 SiO2 thickness dependences 35 -- 3 Quasi?-ballistic Transport in Si Nanoscale MOSFETs 41 -- 3.1 A picture of quasi?-ballistic transport simulated using quantum?-corrected Monte Carlo simulation 41 -- 3.1.1 Device structure and simulation method 42 -- 3.1.2 Scattering rates for 3?-D electron gas 44 -- 3.1.3 Ballistic transport limit 46 -- 3.1.4 Quasi?-ballistic transport 50 -- 3.1.5 Role of elastic and inelastic phonon scattering 51 -- 3.2 Multi?-sub?-band Monte Carlo simulation considering quantum confinement in inversion layers 55 -- 3.2.1 Scattering Rates for 2?-D Electron Gas 56 -- 3.2.2 Increase in Dac for SOI MOSFETs 58 -- 3.2.3 Simulated electron mobilities in bulk Si and SOI MOSFETs 59 -- 3.2.4 Electrical characteristics of Si DG?-MOSFETs 61 -- 3.3 Extraction of quasi?-ballistic transport parameters in Si DG?-MOSFETs 64 -- 3.3.1 Backscattering coefficient 64 -- 3.3.2 Current drive 66 -- 3.3.3 Gate and drain bias dependences 67 -- 3.4 Quasi?-ballistic transport in Si junctionless transistors 69 -- 3.4.1 Device structure and simulation conditions 70 -- 3.4.2 Influence of SR scattering 71 -- 3.4.3 Influence of II scattering 74 -- 3.4.4 Backscattering coefficient 75 -- 3.5 Quasi?-ballistic transport in GAA?-Si nanowire MOSFETs 76 -- 3.5.1 Device structure and 3DMSB?-MC method 76 -- 3.5.2 Scattering rates for 1?-D electron gas 77.

3.5.3 ID-VG characteristics and backscattering coefficient 79 -- 4 Phonon Transport in Si Nanostructures 85 -- 4.1 Monte Carlo simulation method 87 -- 4.1.1 Phonon dispersion model 87 -- 4.1.2 Particle simulation of phonon transport 88 -- 4.1.3 Free flight and scattering 89 -- 4.2 Simulation of thermal conductivity 91 -- 4.2.1 Thermal conductivity of bulk silicon 91 -- 4.2.2 Thermal conductivity of silicon thin films 94 -- 4.2.3 Thermal conductivity of silicon nanowires 98 -- 4.2.4 Discussion on Boundary scattering effect 100 -- 4.3 Simulation of heat conduction in devices 102 -- 4.3.1 Simulation method 102 -- 4.3.2 Simple 1?-D structure 103 -- 4.3.3 FinFET structure 106 -- 5 Carrier Transport in High?-mobility MOSFETs 112 -- 5.1 Quantum?-corrected MC Simulation of High?-mobility MOSFETs 112 -- 5.1.1 Device Structure and Band Structures of Materials 112 -- 5.1.2 Band Parameters of Si, Ge, and III?-V Semiconductors 114 -- 5.1.3 Polar?-optical Phonon (POP) Scattering in III?-V Semiconductors 115 -- 5.1.4 Advantage of UTB Structure 116 -- 5.1.5 Drive Current of III?-V, Ge and Si n?-MOSFETs 119 -- 5.2 Source?-drain Direct Tunneling in Ultrascaled MOSFETs 124 -- 5.3 Wigner Monte Carlo (WMC) Method 125 -- 5.3.1 Wigner Transport Formalism 126 -- 5.3.2 Relation with Quantum?-corrected MC Method 129 -- 5.3.3 WMC Algorithm 131 -- 5.3.4 Description of Higher?-order Quantized Subbands 133 -- 5.3.5 Application to Resonant?-tunneling Diode 133 -- 5.4 Quantum Transport Simulation of III?-V n?-MOSFETs with Multi?-subband WMC (MSB?-WMC) Method 138 -- 5.4.1 Device Structure 138 -- 5.4.2 POP Scattering Rate for 2?-D Electron Gas 139 -- 5.4.3 ID-VG Characteristics for InGaAs DG?-MOSFETs 139 -- 5.4.4 Channel Length Dependence of SDT Leakage Current 143 -- 5.4.5 Effective Mass Dependence of Subthreshold Current Properties 144 -- 6 Atomistic Simulations of Si, Ge and III?-V Nanowire MOSFETs 151 -- 6.1 Phonon?-limited electron mobility in Si nanowires 151 -- 6.1.1 Band structure calculations 152.

6.1.2 Electron?-phonon interaction 161 -- 6.1.3 Electron mobility 162 -- 6.2 Comparison of phonon?-limited electron mobilities between Si and Ge nanowires 168 -- 6.3 Ballistic performances of Si and InAs nanowire MOSFETs 173 -- 6.3.1 Band structures 174 -- 6.3.2 Top?-of?-the?-barrier model 174 -- 6.3.3 ID-VG characteristics 177 -- 6.3.4 Quantum capacitances 178 -- 6.3.5 Power?-delay?-product 179 -- 6.4 Ballistic performances of InSb, InAs, and GaSb nanowire MOSFETs 181 -- 6.4.1 Band structures 182 -- 6.4.2 ID-VG characteristics 182 -- 6.4.3 Power?-delay?-product 186 -- Appendix A: Atomistic Poisson equation 187 -- Appendix B: Analytical expressions of electron?-phonon interaction Hamiltonian matrices 188 -- 7 2?-D Materials and Devices 191 -- 7.1 2?-D Materials 191 -- 7.1.1 Fundamental Properties of Graphene, Silicene and Germanene 192 -- 7.1.2 Features of 2?-D Materials as an FET Channel 197 -- 7.2 Graphene Nanostructures with a Bandgap 198 -- 7.2.1 Armchair?-edged Graphene Nanoribbons (A?-GNRs) 199 -- 7.2.2 Relaxation Effects of Edge Atoms 203 -- 7.2.3 Electrical Properties of A?-GNR?-FETs Under Ballistic Transport 205 -- 7.2.4 Bilayer Graphenes (BLGs) 209 -- 7.2.5 Graphene Nanomeshes (GNMs) 214 -- 7.3 Influence of Bandgap Opening on Ballistic Electron Transport in BLG and A?-GNR?-MOSFETs 215 -- 7.3.1 Small Bandgap Regime 217 -- 7.3.2 Large Bandgap Regime 219 -- 7.4 Silicene, Germanene and Graphene Nanoribbons 221 -- 7.4.1 Bandgap vs Ribbon Width 222 -- 7.4.2 Comparison of Band Structures 222 -- 7.5 Ballistic MOSFETs with Silicene, Germanene and Graphene nanoribbons 223 -- 7.5.1 ID-VG Characteristics 223 -- 7.5.2 Quantum Capacitances 224 -- 7.5.3 Channel Charge Density and Average Electron Velocity 225 -- 7.5.4 Source?-drain Direct Tunneling (SDT) 226 -- 7.6 Electron Mobility Calculation for Graphene on Substrates 228 -- 7.6.1 Band Structure 229 -- 7.6.2 Scattering Mechanisms 229 -- 7.6.3 Carrier Degeneracy 231 -- 7.6.4 Electron Mobility Considering Surface Optical Phonon Scattering of Substrates 232.

7.6.5 Electron Mobility Considering Charged Impurity Scattering 234 -- 7.7 Germanane MOSFETs 236 -- 7.7.1 Atomic Model for Germanane Nanoribbon Structure 237 -- 7.7.2 Band Structure and Electron Effective Mass 238 -- 7.7.3 Electron Mobility 240 -- Appendix A: Density?-of?-states for Carriers in Graphene 242 -- References 242 -- Index 247.