Contents 6.JFET and MESFET 153 61. The JFET 153 6. 2. The MESFET Important Equations.... 163 7. The Mos Transistor 165 7.1. Introduction and basic principles……… 165 7.2. The Mos capacitor…… 170 7. 2.1. Accumulation 7.2.2. Depletion ,176 7. 2. 3. Inversion 178 73. Threshold voltage 183 7.3.1 Ideal threshold voltage. 183 7.3.2. Flat-band voltage 7.3.3. Threshold voltage. 187 7. 4. Current in the mos transistor 187 7.4.1. Influence of substrate bias on threshold voltage 192 7.4.2. Simplified model 194 7.5. Surface mobility.... 7.6. Carrier velocity saturation 199 77. Subthreshold current- Subthreshold slope………………201 7. 8. Continuous model 206 7.9. Channel length modulation 7.10. Numerical modeling of the mos transistor 210 711. Short-channel effect 213 7. 12. Hot-carrier degradation 7. 12.1. Scaling rules 216 7. 12.2. Hot electrons 218 7. 12.3. Substrate current 218 7.12.4. Gate current 219 7. 12.5. Degradation mechanism 7.13. Terminal capacitances…… 7. 14. Particular mosfet structures 224 7.14.1. Non-Volatile Memory MOSFETs 224 7. 14.2. SOI MOSFETS 228 7. 15. Advanced MOSFET concepts 7.15.1. Polysilicon depletion…… 230 7. 15.2. High-k dielectrics.. 231 7.15.3. Drain-induced barrier lowering dIBl) 231 7.154. Gate-induced drain leakage(GDL……………………232 7.15.5. Reverse short-channel effect 7.15.6. Quantization effects in the inversion channel .234 Important Equatio ProblemsContents vii 6. 6.1. 6.2. 7. 7.1. 7.2. 7.2.1. 7.2.2. 7.2.3. 7.3. 7.3.1 7.3.2. 7.3.3. 7.4. 7.4.1. 7.4.2. 7.5. 7.6. 7.7. 7.8. 7.9. 7.10. 7.11. 7.12. 7.12.1. 7.12.2. 7.12.3. 7.12.4. 7.12.5. 7.13. 7.14. 7.14.1. 7.14.2. 7.15. 7.15.1. 7.15.2. 7.15.3. 7.15.4. 7.15.5. 7.15.6. JFET and MESFET The JFET The MESFET Important Equations The MOS Transistor Introduction and basic principles The MOS capacitor Accumulation Depletion Inversion Threshold voltage Ideal threshold voltage Flat-band voltage Threshold voltage Current in the MOS transistor Influence of substrate bias on threshold voltage Simplified model Surface mobility Carrier velocity saturation Subthreshold current - Subthreshold slope Continuous model Channel length modulation Numerical modeling of the MOS transistor Short-channel effect Hot-carrier degradation Scaling rules Hot electrons Substrate current Gate current Degradation mechanism Terminal capacitances Particular MOSFET structures Non-Volatile Memory MOSFETs SOI MOSFETs Advanced MOSFET concepts Polysilicon depletion High-k dielectrics Drain-induced barrier lowering (DIBL) Gate-induced drain leakage (GIDL) Reverse short-channel effect Quantization effects in the inversion channel Important Equations Problems 153 153 159 163 165 165 170 170 176 178 183 183 184 187 187 192 194 196 199 201 206 208 210 213 216 216 218 218 219 220 221 224 224 228 230 230 231 231 232 233 234 235 236