Semiconductor Basics

Acknowledgements xiii Introduction xv 1 The Bohr Atom 1 Objectives of This Chapter 1 1.1 Sinusoidal Waves 1 1.2 The Case of the Missing Lines 3 1.3 The Strange Behavior of Spectra from Gases and Metals 4 1.4 The Classifications of Basic Elements 5 1.5 The Hydrogen Spectrum Lines 5 1.6 Light is a Particle 7 1.7 The Atom’s Structure 8 1.8 The Bohr Atom 10 1.9 Summary and Conclusions 13 Appendix 1.1 Some Details of the Bohr Model 14 Appendix 1.2 Semiconductor Materials 16 Appendix 1.3 Calculating the Rydberg Constant 16 2 Energy Bands 19 Objectives of This Chapter 19 2.1 Bringing Atoms Together 19 2.2 The Insulator 22 2.3 The Conductor 23 2.4 The Semiconductor 24 2.5 Digression: Water Analogy 27 2.6 The Mobility of Charges 27 2.7 Summary and Conclusions 28 Appendix 2.1 Energy Gap in Semiconductors 29 Appendix 2.2 Number of Electrons and the Fermi Function 29 3 Types of Semiconductors 35 Objectives of This Chapter 35 3.1 Semiconductor Materials 35 3.2 Short Summary of Semiconductor Materials 36 3.2.1 Silicon 36 3.2.2 Germanium 37 3.2.3 Gallium Arsenide 39 3.3 Intrinsic Semiconductors 39 3.4 Doped Semiconductors: n-Type 40 3.5 Doped Semiconductors: p-Type 43 3.6 Additional Considerations 45 3.7 Summary and Conclusions 47 Appendix 3.1 The Fermi Levels in Doped Semiconductors 48 Appendix 3.2 Why All Donor Electrons go to the Conduction Band 50 4 Infrared Detectors 51 Objectives of This Chapter 51 4.1 What is Infrared Radiation? 51 4.2 What Our Eyes Can See 54 4.3 Infrared Applications 55 4.4 Types of Infrared Radiation 58 4.5 Extrinsic Silicon Infrared Detectors 58 4.6 Intrinsic Infrared Detectors 62 4.7 Summary and Conclusions 63 Appendix 4.1 Light Diffraction 64 Appendix 4.2 Blackbody Radiation 66 5 The pn-Junction 69 Objectives of This Chapter 69 5.1 The pn-Junction 69 5.2 The Semiconductor Diode 72 5.3 The Schottky Diode 76 5.4 The Zener or Tunnel Diode 77 5.5 Summary and Conclusions 81 Appendix 5.1 Fermi Levels of a pn-Junction 81 Appendix 5.2 Diffusion and Drift Currents 82 Appendix 5.3 The Thickness of the Transition Region 83 Appendix 5.4 Work Function and the Schottky Diode 85 6 Other Electrical Components 89 Objectives of This Chapter 89 6.1 Voltage and Current 89 6.2 Resistance 90 6.3 The Capacitor 93 6.4 The Inductor 96 6.5 Sinusoidal Voltage 98 6.6 Inductor Applications 99 6.7 Summary and Conclusions 102 Appendix 6.1 Impedance and Phase Changes 102 7 Diode Applications 105 Objectives of This Chapter 105 7.1 Solar Cells 105 7.2 Rectifiers 106 7.3 Current Protection Circuit 109 7.4 Clamping Circuit 109 7.5 Voltage Clipper 110 7.6 Half-wave Voltage Doubler 111 7.7 Solar Cells Bypass Diodes 113 7.8 Applications of Schottky Diodes 113 7.9 Applications of Zener Diodes 114 7.10 Summary and Conclusions 115 Appendix 7.1 Calculation of the Current Through an RC Circuit 115 8 Transistors 117 Objectives of This Chapter 117 8.1 The Concept of the Transistor 117 8.2 The Bipolar Junction Transistor 118 8.3 The Junction Field-effect Transistor 124 8.4 The Metal Oxide Semiconductor FET 128 8.5 Summary and Conclusions 132 Appendix 8.1 Punch Trough 134 9 Transistor Biasing Circuits 135 Objectives of This Chapter 135 9.1 Introduction 135 9.2 Emitter Feedback Bias 136 9.3 Sinusoidal Operation of a Transistor with Emitter Bias 140 9.4 The Fixed Bias Circuit 144 9.5 The Collector Feedback Bias Circuit 147 9.6 Power Considerations 148 9.7 Multistage Transistor Amplifiers 149 9.8 Operational Amplifiers 150 9.9 The Ideal OpAmp 153 9.10 Summary and Conclusions 155 Appendix 9.1 Derivation of the Stability of the Collector Feedback Circuit 156 10 Integrated Circuit Fabrication 159 Objectives of This Chapter 159 10.1 The Basic Material 159 10.2 The Boule 160 10.2.1 The Czochralski Method 160 10.2.2 The Flow-zone Method 161 10.3 Wafers and Epitaxial Growth 162 10.4 Photolithography 162 10.5 The Fabrication of a pnp Transistor on a Silicon Wafer 163 10.6 A Digression on Doping 166 10.6.1 Thermal Diffusion 166 10.6.2 Implantation 167 10.7 Resume the Transistor Processing 170 10.7.1 The Contacts 170 10.7.2 Metallization 170 10.7.3 Multiple Interconnects 171 10.8 Fabrication of Other Components 172 10.8.1 The Integrated Resistor 172 10.8.2 The Integrated Capacitor 173 10.8.3 The Integrated Inductor 173 10.9 Testing and Packaging 174 10.10 Clean Rooms 178 10.11 Additional Thoughts About Processing 180 10.12 Summary and Conclusions 181 Appendix 10.1 Miller Indices in the Diamond Structure 183 11 Logic Circuits 187 Objectives of This Chapter 187 11.1 Boolean Algebra 187 11.2 Logic Symbols and Relay Circuits 188 11.3 The Electronics Inside the Symbols 190 11.3.1 Diode Implementation 191 11.3.2 CMOS Implementation 192 11.4 The Inverter or NOT Circuit 192 11.5 The NOR Circuit 193 11.6 The NAND Circuit 195 11.7 The XNOR or Exclusive NOR 196 11.8 The Half Adder 197 11.9 The Full Adder 198 11.10 Adding More than Two Digital Numbers 198 11.11 The Subtractor 199 11.12 Digression: Flip-flops, Latches, and Shifters 201 11.13 Multiplication and Division of Binary Numbers 203 11.14 Additional Comments: Speed and Power 204 11.15 Summary and Conclusions 206 Appendix 11.1 Algebraic Formulation of Logic Modules 206 Appendix 11.2 Detailed Analysis of the Full Adder 207 Appendix 11.3 Complementary Numbers 208 Appendix 11.4 Dividing Digital Numbers 209 Appendix 11.5 The Author’s Symbolic Logic Machine Using Relays 210 12 VLSI Components 211 Objectives of This Chapter 211 12.1 Multiplexers 211 12.2 Demultiplexers 213 12.3 Registers 214 12.4 Timing and Waveforms 216 12.5 Memories 218 12.5.1 Static Random-access Memory 219 12.5.2 Dynamic Random-access Memory 222 12.5.3 Read-only Memory 224 12.5.4 Programable Read-only Memory 225 12.6 Gate Arrays 227 12.7 Summary and Conclusions 227 Appendix 12.1 A NAND implementation of a 2 to 1 MUX 228 13 Optoelectronics 229 Objectives of This Chapter 229 13.1 Photoconductors 229 13.2 PIN Diodes 230 13.3 LASERs 231 13.3.1 Laser Action 231 13.3.2 Solid-state Lasers 234 13.3.3 Semiconductor LASERs 234 13.3.4 LASER Applications 237 13.4 Light-emitting Diodes 238 13.5 Summary and Conclusions 240 Appendix 13.1 The Detector Readout 240 14 Microprocessors and Modern Electronics 243 Objectives of This Chapter 243 14.1 The Computer 243 14.1.1 Computer Architecture 243 14.1.2 Memories 244 14.1.3 Input and Output Units 246 14.1.4 The Central Processing Unit 246 14.2 Microcontrollers 248 14.3 Liquid Crystal Displays 249 14.3.1 Liquid Crystal Materials 249 14.3.2 Contacts 251 14.3.3 Color Filters 251 14.3.4 Thin-film Transistors 251 14.3.5 The Glass 253 14.3.6 Polarizers 253 14.3.7 The Source of Light 254 14.3.8 The Entire Operation 254 14.4 Summary and Conclusions 255 Appendix 14.1 Keyboard Codes 256 15 The Future 257 Objectives of This Chapter 257 15.1 The Past 257 15.2 Problems with Silicon-based Technology 262 15.3 New Technologies 265 15.3.1 Nanotubes 265 15.3.2 Quantum Computing 266 15.3.3 Biocomputing 268 15.4 Silicon Technology Innovations 268 15.4.1 Process Improvements 269 15.4.2 Vertical Integration 269 15.4.3 The FinFET 271 15.4.4 The Tunnel FET 271 15.5 Summary and Conclusions 272 Epilogue 273 Appendix A Useful Constants 275 Appendix B Properties of Silicon 277 Appendix C List of Acronyms 279 Additional Reading and Sources 285 Index 289