Advanced Physical Models for Silicon Device Simulation

1 Simulation of Silicon Devices: An Overview.- 1.1 Transport Models.- 1.1.1 Quantum Transport.- 1.1.2 Boltzmann Equation.- 1.1.3 Method of Moments.- 1.1.3.1 Transport Models.- 1.1.4 Thermodynamic Approach.- 1.2 Review of Physical Models for Drift-Diffusion Equations.- 1.2.1 Effective Intrinsic Density.- 1.2.1.1 Effective Masses and Effective Densities of States.- 1.2.1.2 Intrinsic Gap and Intrinsic Carrier Density.- 1.2.1.3 Band Gap Narrowing: Theoretical Models.- 1.2.1.4 Band Gap Narrowing: Empirical Models.- 1.2.1.5 Effective Intrinsic Density with Fermi Statistics.- 1.2.2 Mobility.- 1.2.2.1 Theoretical Background.- 1.2.2.2 Empirical Models for the Low Field Mobility.- 1.2.2.3 Empirical High-Field Corrections.- 1.2.2.4 Some Remarks.- 1.2.3 Generation-Recombination.- 1.2.3.1 Shockley-Read-Hall Recombination.- 1.2.3.2 Auger Recombination.- 1.2.3.3 Impact Ionization.- 1.3 Simulation Example: Gated Diode.- References.- 2 Mobility Model for Hydrodynamic Transport Equations.- 2.1 Analytical Model of the Electron Mobility.- 2.1.1 Variational Method with a Heated Maxwellian.- 2.1.2 Scattering Mechanisms.- 2.1.2.1 Intravalley Acoustic-Phonon Scattering.- 2.1.2.2 Intervalley Scattering.- 2.1.2.3 Impurity Scattering.- 2.1.3 Analytical Results for the Partial Mobilities.- 2.1.3.1 Non-Elastic Approach for Intravalley Acoustic-Phonon Scattering.- 2.1.3.2 Intervalley Scattering.- 2.1.3.3 Impurity Scattering Including Dispersive Screening.- 2.2 Parameter Fit and Comparison with Experimental Data.- 2.2.1 Fit Procedure.- 2.2.2 Dependence on Ambient Temperature.- 2.2.3 Dependence on Carrier Temperature, Velocity Saturation.- 2.2.4 Doping Dependence.- 2.3 Hole Mobility.- 2.3.1 Band Model.- 2.3.2 Analytical Model for the Hole Mobility.- 2.3.3 Dependence on Ambient Temperature, Carrier Temperature, and Doping.- 2.4 Simulation Results.- References.- 3 Advanced Generation-Recombination Models.- 3.1 Band-to-Band Tunneling.- 3.1.1 Microscopic Model.- 3.1.1.1 Kubo Formalism for the Tunneling Conductivity.- 3.1.1.2 Direct (Zero Phonon) Transitions.- 3.1.1.3 Indirect (Phonon-Assisted) Transitions.- 3.1.2 Model for Device Simulation.- 3.1.2.1 Simplifications.- 3.1.2.2 Comparison of Direct and Indirect Band-to-Band Tunneling.- 3.1.3 Field and Angular Dependence.- 3.2 Defect-Assisted Tunneling.- 3.2.1 Field Enhancement Factors for SRH Lifetimes.- 3.2.2 Simplified Models of the Field Enhancement.- 3.2.2.1 High-Temperature Approximation.- 3.2.2.2 Low-Temperature Approximation.- 3.2.3 On the Temperature Dependence of SRH Lifetimes.- 3.2.3.1 High-Temperature Approximation.- 3.2.3.2 Low-Temperature Approximation.- 3.2.4 Example: The Gold Acceptor in Silicon.- 3.3 Numerical Simulation of Tunnel Generation Currents.- 3.3.1 Band-to-Band Tunneling versus Defect-Assisted Tunneling.- 3.3.2 Local versus Nonlocal Description.- 3.4 Coupled Defect-Level Recombination.- 3.4.1 Theory of Coupled Defect-Level Recombination.- 3.4.1.1 Steady-State Recombination Rate.- 3.4.1.2 Field-Enhancement of the Coupled Defect-Level Rate.- 3.4.2 Simulation of LPE-Grown Junctions.- 3.4.3 Effect of Different Two-Level Systems.- References.- 4 Metal-Semiconductor Contact.- 4.1 Emission Current Through a Parabolic Barrier.- 4.2 Interpolation Scheme for the Transmission Probability.- 4.3 Analytical Model of the Contact Current.- 4.4 Boundary Conditions for Device Simulation.- 4.5 Comparison with Measurements.- 4.6 Results of Numerical Simulation.- 4.6.1 Implementation.- 4.6.2 Schottky nin Diode.- 4.6.3 Merged pin/Schottky (MPS) Diode.- References.- 5 Modeling Transport Across Thin Dielectric Barriers.- 5.1 One-Step Tunneling.- 5.1.1 Transmission Probability.- 5.1.2 I (V)-Characteristics of Direct and FN Tunneling.- 5.2 Two-Step Multiphonon-Assisted Tunneling.- 5.3 Resonant Tunneling.- 5.4 Comparison of Two-Step Zero-Phonon Tunneling and Resonant Tunneling.- 5.5 Simulation of the Long-Term Charge Loss in EPROMs.- 5.5.1 Measurements.- 5.5.2 Simulated Field and High-Temperature Dependence of the Leakage Current.- 5.5.3 Comparison of Various Loss Mechanisms.- References.- 6 Summary and Outlook.- References.- Appendices.- B Evaluation of a Double Integral.- C Transmission Probability for a Parabolic Barrier.- D Asymptotic Forms and Interpolation of Cylinder Functions.- E Energy Limit for Gaussian Approximation.- G Probability of Resonant Tunneling.- References.- List of Figures.- List of Tables.