CONTENTS Preface. Energy Band Theory.. Electron in a crystal... Two examples of electron behavior... Free electron...2. The particle-in-a-box approach..2. Energy bands of a crystal (intuitive approach)..3. Krönig-Penney model..4. Valence band and conduction band..5. Parabolic band approximation..6. Concept of a hole..7. Effective mass of the electron in a crystal..8. Density of states in energy bands.2. Intrinsic semiconductor.3. Extrinsic semiconductor Ionization of impurity atoms Electron-hole equilibrium Calculation of the Fermi Level Degenerate semiconductor.3...3.2..3.3..3.4..4. Alignment of Fermi levels 2. Theory of Electrical Conduction 2.. Drift of electrons in an electric field 2.2. Mobility 2.3. Drift current 2.3.. Hall effect 2.4. Diffusion current 2.5. Drift-diffusion equations 2.5.. Einstein relationships 2.6. Transport equations 2.7. Quasi-Fermi levels xi 3 6 7 5 9 20 2 25 29 3 34 35 37 39 40 43 44 5 5 53 56 57 59 60 60 62 65 67 68
vi Contents 3. Generation/Recombination Phenomena 3.. Introduction 3.2. Direct and indirect transitions 3.3. Generation/recombination centers 3.4. Excess carrier lifetime 3.5. SRH recombination 3.5.. Minority carrier lifetime 3.6. Surface recombination 4. The PN Junction Diode 4.. Introduction 4.2. Unbiased PN junction 4.3. Biased PN junction 4.4. 4.4.. 4.4.2. 4.4.3. 4.4.4. 4.5. Current-voltage characteristics Derivation of the ideal diode model Generation/recombination current Junction breakdown Short-base diode PN junction capacitance 4.5.. Transition capacitance 4.5.2. Diffusion capacitance 4.5.3. Charge storage and switching time 4.6. Models for the PN junction 4.6.. 4.6.2. 4.6.3. Quasi-static, large-signal model Small-signal, low-frequency model Small-signal, high-frequency model 4.7. Solar cell 4.8. PiN diode 5. Metal-semiconductor contacts 5.. Schottky diode 5... Energy band diagram 5..2. Extension of the depletion region 5..3. Schottky effect 5..4. Current-voltage characteristics 5..5. Influence of interface states 5..6. Comparison with the PN junction 5.2. Ohmic contact 73 73 74 77 79 82 86 87 89 89 95 95 97 03 05 07 3 6 8 20 20 2 23 25 26 26 28 28 32 33 33 39 39 39 42 43 45 46 47 49 50 5
Contents 6. JFET and MESFET 6.. The JFET 6.2. The MESFET 7. The MOS Transistor 7.. Introduction and basic principles 7.2. The MOS capacitor 7.2.. Accumulation 7.2.2. Depletion 7.2.3. Inversion 7.3. 7.3. 7.3.2. 7.3.3. 7.4. Current in the MOS transistor 7.4.. 7.4.2. 7.5. 7.6. 7.7. 7.8. 7.9. Channel length modulation 7.0. 7.. 7.2. Threshold voltage Ideal threshold voltage Flat-band voltage Threshold voltage 7.2.. 7.2.2. 7.2.3. 7.2.4. 7.2.5. Influence of substrate bias on threshold voltage Simplified model Surface mobility Carrier velocity saturation Subthreshold current - Subthreshold slope Continuous model Numerical modeling of the MOS transistor Short-channel effect Hot-carrier degradation Scaling rules Hot electrons Substrate current Gate current Degradation mechanism 7.3. Terminal capacitances 7.4. Particular MOSFET structures 7.4.. Non-Volatile Memory MOSFETs 7.4.2. SOI MOSFETs 7.5. Advanced MOSFET concepts 7.5.. 7.5.2. 7.5.3. 7.5.4. 7.5.5. 7.5.6. 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 vii 53 53 59 63 65 65 70 70 76 78 83 83 84 87 87 92 94 96 99 20 206 208 20 23 26 26 28 28 29 220 22 224 224 228 230 230 23 23 232 233 234 235 236
viii 8. The Bipolar Transistor 8.. Introduction and basic principles 8... Long-base device 8..2. Short-base device 8..3. Fabrication process Amplification using a bipolar transistor Ebers-Moll model 8.3.. Emitter efficiency 8.3.2. Transport factor in the base Regimes of operation Transport model 8.2. 8.3. 8.4. 8.5. 8.6. Gummel-Poon model 8.6.. Current gain 8.6... Recombination in the base 8.6..2. Emitter efficiency and current gain 8.7. Early effect 8.8. Dependence of current gain on collector current 8.8.. Recombination at the emitter-base junction 8.8.2. Kirk effect 8.9. Base resistance 8.0. Numerical simulation of the bipolar transistor 8.. Collector junction breakdown 8... Common-base configuration 8..2. Common-emitter configuration 8.2. Charge-control model 8.2.. Forward active mode 8.2.2. Large-signal model 8.2.3. Small-signal model 9. Heterojunction Devices 9.. Concept of a heterojunction 9... Energy band diagram 9.2. 9.2. 9.3. Photonic Devices Heterojunction bipolar transistor (HBT) High electron mobility transistor (HEMT) 9.3.. 9.3.2. Light-emitting diode (LED) Laser diode Contents 25 25 252 253 256 258 259 268 269 272 273 275 280 280 282 286 290 290 292 295 295 298 298 299 300 30 306 307 309 309 35 35 36 320 32 324 324 326 330
Contents 0. Quantum-Effect Devices 0.. Tunnel Diode 0... Tunnel effect 0..2. Tunnel diode 0.2. Low-dimensional devices 0.2.. Energy bands 0.2.2. Density of states 0.2.3. Conductance of a D semiconductor sample 0.2.4. 2D and D MOS transistors 0.3. 0.3.. 0.3.2. 0.3.3.. Semiconductor Processing...2..3. Doping techniques.4..5..6..7..8. Single-electron transistor Tunnel junction Double tunnel junction Single-electron transistor Semiconductor materials Silicon crystal growth and refining.3.. Ion implantation.3.2. Doping impurity diffusion.3.3. Gas-phase diffusion Oxidation Chemical vapor deposition (CVD).5.. Silicon deposition and epitaxy.5.2. Dielectric layer deposition Photolithography Etching Metallization.8.2. Metal deposition.8.3. Metal silicides.9. CMOS process.0. NPN bipolar process 2. Annex Al. A2. A3. A4. A5. A6. A7. Index Physical Quantities and Units Physical Constants Concepts of Quantum Mechanics Crystallography Reciprocal Space Getting Started with Matlab Greek alphabet Basic Differential Equations ix 33 33 33 333 336 337 343 348 350 353 353 355 358 36 363 363 364 367 367 370 373 374 38 38 382 384 388 39 39 392 393 399 405 409 409 40 4 44 48 426 427 43