Semiconductor Physics and Devices Basic Principles Fourth Edition Donald A. Neamen University of New Mexico TM nea29583_fm_i-xxiv.indd i 12/11/10 1:01 PM TM SEMICONDUCTOR PHYSICS & DEVICES: BASIC PRINCIPLES, FOURTH EDITION Published by McGraw-Hill, a business unit of The McGraw-Hill Companies, Inc., 1221 Avenue of the Americas, New York, NY 10020. Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved.
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1 2 3 4 5 6 7 8 9 0 DOC/DOC 1 0 9 8 7 6 5 4 3 2 1 ISBN 978-0-07-352958-5 MHID 0-07-352958-3 Vice President & Editor-in-Chief: Marty Lange Vice President EDP/Central Publishing Services: Kimberly Meriwether David Publisher: Raghu Srinivasan Sponsoring Editor: Peter E. Massar Marketing Manager: Curt Reynolds Development Editor: Lora Neyens Project Manager: Melissa M. Leick Design Coordinator: Brenda A. Rolwes Cover Designer: Studio Montage, St.
Louis, Missouri Cover Image: © Getty Images RF Buyer: Sherry L. Kane Media Project Manager: Balaji Sundararaman Compositor: MPS Limited, a Macmillan Company Typeface: 10/12 Times Roman Printer: RR Donnelley, Crawfordsville All credits appearing on page or at the end of the book are considered to be an extension of the copyright page. Library of Congress Cataloging-in-Publication Data Neamen, Donald A. Semiconductor physics and devices : basic principles / Donald A.com nea29583_fm_i-xxiv.indd ii 12/11/10 1:01 PM ABOUT THE AUTHOR Donald A.
Neamen is a professor emeritus in the Department of Electrical and Computer Engineering at the University of New Mexico where he taught for more than 25 years. He received his Ph. from the University of New Mexico and then became an electronics engineer at the Solid State Sciences Laboratory at Hanscom Air Force Base. In 1976, he joined the faculty in the ECE department at the University of New Mexico, where he specialized in teaching semiconductor physics and devices courses and electronic circuits courses.
He is still a part-time instructor in the depart- ment. He also recently taught for a semester at the University of Michigan-Shanghai Jiao Tong University (UM-SJTU) Joint Institute in Shanghai, China. In 1980, Professor Neamen received the Outstanding Teacher Award for the University of New Mexico. In 1983 and 1985, he was recognized as Outstanding Teacher in the College of Engineering by Tau Beta Pi.
In 1990, and each year from 1994 through 2001, he received the Faculty Recognition Award, presented by gradu- ating ECE students. He was also honored with the Teaching Excellence Award in the College of Engineering in 1994. In addition to his teaching, Professor Neamen served as Associate Chair of the ECE department for several years and has also worked in industry with Martin Marietta, Sandia National Laboratories, and Raytheon Company. He has published many papers and is the author of Microelectronics Circuit Analysis and Design, 4th edition, and An Introduction to Semiconductor Devices.
nea29583_fm_i-xxiv.indd iii 12/11/10 1:01 PM CONTENTS Preface x 2.2 Schrodinger’s Wave Equation 31 Prologue—Semiconductors and the Integrated 2.1 The Wave Equation 31 Circuit xvii 2.2 Physical Meaning of the Wave Function 32 2.3 Boundary Conditions 33 P A R T I—Semiconductor Material Properties 2.3 Applications of Schrodinger’s Wave CHAPTER 1 Equation 34 The Crystal Structure of Solids 1 2.1 Electron in Free Space 35 2.2 The Infinite Potential Well 36 1.3 The Step Potential Function 39 1.4 The Potential Barrier and Tunneling 44 1.2 Types of Solids 2 2.4 Extensions of the Wave Theory 1.3 Space Lattices 3 to Atoms 46 1.1 Primitive and Unit Cell 3 2.1 The One-Electron Atom 46 1.2 Basic Crystal Structures 4 2.2 The Periodic Table 50 1.3 Crystal Planes and Miller Indices 6 2.4 Directions in Crystals 9 Problems 52 1.4 The Diamond Structure 10 1.5 Atomic Bonding 12 CHAPTER 3 *1.6 Imperfections and Impurities in Solids 14 Introduction to the Quantum Theory 1.1 Imperfections in Solids 14 of Solids 58 1.2 Impurities in Solids 16 *1.7 Growth of Semiconductor Materials 17 3.1 Growth from a Melt 17 3.1 Allowed and Forbidden Energy Bands 59 1.1 Formation of Energy Bands 59 1.2 The Kronig–Penney Model 63 Problems 21 3.3 The k-Space Diagram 67 3.2 Electrical Conduction in Solids 72 3.1 The Energy Band and the Bond Model 72 CHAPTER 2 3.2 Drift Current 74 Introduction to Quantum Mechanics 25 3.3 Electron Effective Mass 75 2.4 Concept of the Hole 78 2.1 Principles of Quantum Mechanics 26 3.5 Metals, Insulators, and Semiconductors 80 2.3 Extension to Three Dimensions 83 2.2 Wave–Particle Duality 27 3.1 The k-Space Diagrams of Si and GaAs 83 2.3 The Uncertainty Principle 30 3.2 Additional Effective Mass Concepts 85 iv nea29583_fm_i-xxiv.indd iv 12/11/10 1:01 PM Contents v 3.4 Density of States Function 85 4.1 Mathematical Derivation 85 Problems 149 3.2 Extension to Semiconductors 88 3.5 Statistical Mechanics 91 CHAPTER 5 3.1 Statistical Laws 91 Carrier Transport Phenomena 156 3.2 The Fermi–Dirac Probability Function 91 3.3 The Distribution Function and the Fermi 5.1 Drift Current Density 157 Problems 100 5.4 Velocity Saturation 169 The Semiconductor in Equilibrium 106 5.1 Diffusion Current Density 172 4.2 Total Current Density 175 4.1 Charge Carriers in Semiconductors 107 5.3 Graded Impurity Distribution 176 4.1 Equilibrium Distribution of Electrons and Holes 107 5.1 Induced Electric Field 176 4.2 The n0 and p0 Equations 109 5.2 The Einstein Relation 178 4.3 The Intrinsic Carrier Concentration 113 *5.4 The Hall Effect 180 4.4 The Intrinsic Fermi-Level Position 116 5.2 Dopant Atoms and Energy Levels 118 Problems 184 4.2 Ionization Energy 120 CHAPTER 6 4.3 Group III–V Semiconductors 122 Nonequilibrium Excess Carriers 4.3 The Extrinsic Semiconductor 123 in Semiconductors 192 4.1 Equilibrium Distribution of Electrons and Holes 123 6.1 Carrier Generation and Recombination 193 *4.3 The Fermi–Dirac Integral 128 6.1 The Semiconductor in Equilibrium 193 4.4 Degenerate and Nondegenerate 6.2 Excess Carrier Generation and Semiconductors 130 Recombination 194 4.4 Statistics of Donors and Acceptors 131 6.2 Characteristics of Excess Carriers 198 4.2 Complete Ionization and Freeze-Out 132 6.2 Time-Dependent Diffusion Equations 199 4.1 Derivation of the Ambipolar Transport 4.2 Equilibrium Electron and Hole Equation 201 Concentrations 136 6.2 Limits of Extrinsic Doping and Low 4.6 Position of Fermi Energy Level 141 Injection 203 4.3 Applications of the Ambipolar Transport 4.2 Variation of EF with Doping Concentration Equation 206 and Temperature 144 6.4 Dielectric Relaxation Time Constant 214 4.3 Relevance of the Fermi Energy 145 *6.5 Haynes–Shockley Experiment 216 nea29583_fm_i-xxiv.indd v 12/11/10 1:01 PM vi Contents 6.4 Quasi-Fermi Energy Levels 219 8.4 Minority Carrier Distribution 283 *6.5 Excess Carrier Lifetime 221 8.5 Ideal pn Junction Current 286 6.1 Shockley–Read–Hall Theory of 8.6 Summary of Physics 290 Recombination 221 8.2 Limits of Extrinsic Doping and Low 8.8 The “Short” Diode 293 Injection 225 8.2 Generation–Recombination Currents and *6.6 Surface Effects 227 High-Injection Levels 295 6.1 Generation–Recombination Currents 296 6.2 Surface Recombination Velocity 229 8.2 High-Level Injection 302 6.3 Small-Signal Model of the pn Junction 304 Problems 233 8.2 Small-Signal Admittance 306 P A R T II—Fundamental Semiconductor Devices 8.3 Equivalent Circuit 313 CHAPTER 7 *8.4 Charge Storage and Diode Transients 314 8.1 The Turn-off Transient 315 The pn Junction 241 8.2 The Turn-on Transient 317 7.5 The Tunnel Diode 318 7.1 Basic Structure of the pn Junction 242 8.2 Zero Applied Bias 243 Problems 323 7.1 Built-in Potential Barrier 243 7.3 Space Charge Width 249 CHAPTER 9 Metal–Semiconductor and Semiconductor 7.3 Reverse Applied Bias 251 Heterojunctions 331 7.1 Space Charge Width and Electric Field 251 7.3 One-Sided Junctions 256 9.1 The Schottky Barrier Diode 332 7.5 Nonuniformly Doped Junctions 262 9.2 Ideal Junction Properties 334 7.1 Linearly Graded Junctions 263 9.3 Nonideal Effects on the Barrier Height 338 7.4 Current–Voltage Relationship 342 7.5 Comparison of the Schottky Barrier Diode and the pn Junction Diode 345 Problems 269 9.2 Metal–Semiconductor Ohmic Contacts 349 9.1 Ideal Nonrectifying Barrier 349 CHAPTER 8 9.2 Tunneling Barrier 351 The pn Junction Diode 276 9.3 Specific Contact Resistance 352 8.1 pn Junction Current 277 9.1 Qualitative Description of Charge Flow 9.2 Energy-Band Diagrams 354 in a pn Junction 277 9.3 Two-Dimensional Electron Gas 356 8.2 Ideal Current–Voltage Relationship 278 *9.5 Current–Voltage Characteristics 363 nea29583_fm_i-xxiv.indd vi 12/11/10 1:01 PM Contents vii 9.2 Channel Length Modulation 446 Problems 365 11.4 Velocity Saturation 452 CHAPTER 10 11.5 Ballistic Transport 453 Fundamentals of the Metal–Oxide– 11.2 MOSFET Scaling 455 Semiconductor Field-Effect Transistor 371 11.1 Constant-Field Scaling 455 11.2 Threshold Voltage—First 10.1 The Two-Terminal MOS Structure 372 11.1 Energy-Band Diagrams 372 11.3 Threshold Voltage Modifications 457 10.2 Depletion Layer Thickness 376 11.1 Short-Channel Effects 457 10.3 Surface Charge Density 380 11.2 Narrow-Channel Effects 461 10.4 Work Function Differences 382 11.4 Additional Electrical Characteristics 464 10.5 Flat-Band Voltage 385 11.2 The Lightly Doped Drain Transistor 470 10.2 Capacitance–Voltage Characteristics 394 11.3 Threshold Adjustment by Ion 10.1 Ideal C–V Characteristics 394 Implantation 472 10.5 Radiation and Hot-Electron Effects 475 10.3 Fixed Oxide and Interface Charge 11.1 Radiation-Induced Oxide Charge 475 Effects 400 11.2 Radiation-Induced Interface States 478 10.3 The Basic MOSFET Operation 403 11.3 Hot-Electron Charging Effects 480 10.2 Current–Voltage Problems 483 Relationship—Concepts 404 *10.3 Current–Voltage Relationship— Mathematical Derivation 410 CHAPTER 12 10.4 Transconductance 418 The Bipolar Transistor 491 10.5 Substrate Bias Effects 419 12.1 The Bipolar Transistor Action 492 10.1 Small-Signal Equivalent Circuit 422 12.1 The Basic Principle of Operation 493 10.2 Frequency Limitation Factors and 12.2 Simplified Transistor Current Relation— Cutoff Frequency 425 Qualitative Discussion 495 *10.5 The CMOS Technology 427 12.3 The Modes of Operation 498 10.4 Amplification with Bipolar Transistors 500 Problems 433 12.2 Minority Carrier Distribution 501 12.1 Forward-Active Mode 502 CHAPTER 11 12.2 Other Modes of Operation 508 Metal–Oxide–Semiconductor Field-Effect 12.3 Transistor Currents and Low-Frequency Transistor: Additional Concepts 443 Common-Base Current Gain 509 12.1 Current Gain—Contributing Factors 509 11.2 Derivation of Transistor Current 11.1 Nonideal Effects 444 Components and Current Gain 11.1 Subthreshold Conduction 444 Factors 512 nea29583_fm_i-xxiv.indd vii 12/11/10 1:01 PM viii Contents 12.4 Example Calculations of the Gain 13.1 Channel Length Modulation 594 Factors 517 13.2 Velocity Saturation Effects 596 12.3 Subthreshold and Gate Current 12.1 Base Width Modulation 522 Effects 596 12.4 Equivalent Circuit and Frequency 12.3 Emitter Bandgap Narrowing 526 Limitations 598 12.1 Small-Signal Equivalent Circuit 598 *12.5 Nonuniform Base Doping 530 13.2 Frequency Limitation Factors and Cutoff 12.6 Breakdown Voltage 531 Frequency 600 12.5 Equivalent Circuit Models 536 *13.5 High Electron Mobility Transistor 602 *12.1 Ebers–Moll Model 537 13.1 Quantum Well Structures 603 12.2 Gummel–Poon Model 540 13.3 Hybrid-Pi Model 541 13.6 Frequency Limitations 545 Problems 611 12.1 Time-Delay Factors 545 12.2 Transistor Cutoff Frequency 546 P A R T III—Specialized Semiconductor Devices 12.7 Large-Signal Switching 549 CHAPTER 14 12.1 Switching Characteristics 549 Optical Devices 618 12.2 The Schottky-Clamped Transistor 551 *12.8 Other Bipolar Transistor Structures 552 14.1 Polysilicon Emitter BJT 552 14.2 Silicon–Germanium Base Transistor 554 14.1 Photon Absorption Coefficient 619 12.3 Heterojunction Bipolar Transistors 556 14.2 Electron–Hole Pair Generation Rate 622 12.2 Solar Cells 624 Problems 560 14.1 The pn Junction Solar Cell 624 14.2 Conversion Efficiency and Solar Concentration 627 CHAPTER 13 14.3 Nonuniform Absorption Effects 628 The Junction Field-Effect Transistor 571 14.4 The Heterojunction Solar Cell 629 13.5 Amorphous Silicon Solar Cells 630 13.1 Basic pn JFET Operation 572 14.2 Basic MESFET Operation 576 14.2 The Device Characteristics 578 14.1 Internal Pinchoff Voltage, Pinchoff 14.4 Avalanche Photodiode 641 Voltage, and Drain-to-Source Saturation 14.2 Ideal DC Current–Voltage Relationship— Electroluminescence 643 Depletion Mode JFET 582 14.3 Materials 646 nea29583_fm_i-xxiv.indd viii 12/13/10 6:09 PM Contents ix 14.5 Light Emitting Diodes 648 15.3 SCR Turn-Off 697 14.1 Generation of Light 648 15.2 Internal Quantum Efficiency 649 15.3 External Quantum Efficiency 650 Problems 703 14.6 Laser Diodes 654 APPENDIX A 14.1 Stimulated Emission and Population Selected List of Symbols 707 Inversion 655 14.