Physics of Semiconductor Devices Physics of Semiconductor Devices Third Edition S. M. Sze Department of Electronics Engineering National Chiao Tung University Hsinchu, Taiwan and Kwok K. Ng Central Laboratory MVC (a subsidiary of ProMOS Technologies,T aiwan) San Jose, California @ZZClE*CE A JOHN WILEY & SONS, JNC., PUBLICATION Description of cover photograph. A scanning electron micrograph of an array of the floating-gate nonvolatile semiconductor memory (NVSM) magnified 100,000 times. NVSM was invented at Bell Telephone Laboratories in 1967. There are more NVSM cells produced annually in the world than any other semiconductor device and, for that matter, any other human-made item. For a discussion of this device, see Chapter 6. Photo courtesy of Macronix International Company, Hsinchu, Taiwan, ROC. Copyright 0 2007 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. 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For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic format. For information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data is available. ISBN-I 3: 978-0-47 1-1 4323-9 ISBN-10: 0-471-14323-5 Printed in the United States of America 1 0 9 8 7 6 5 4 3 2 1 Preface Since the mid-20th Century the electronics industry has enjoyed phenomenal growth and is now the largest industry in the world. The foundation of the electronics industry is the semiconductor device. To meet the tremendous demand of this industry, the semiconductor-device field has also grown rapidly. Coincident with this growth, the semiconductor-device literature has expanded and diversified. For access to this massive amount of information, there is a need for a book giving a comprehen- sive introductory account of device physics and operational principles. With the intention of meeting such a need, the First Edition and the Second Edition of Physics of Semiconductor Devices were published in 1969 and 198 1, respectively. It is perhaps somewhat surprising that the book has so long held its place as one of the main textbooks for advanced undergraduate and graduate students in applied physics, electrical and electronics engineering, and materials science. Because the book includes much useful information on material parameters and device physics, it is also a major reference for engineers and scientists in semicon- ductor-device research and development. To date, the book is one of the most, if not the most, cited works in contemporary engineering and applied science with over 15,000 citations (ISI, Thomson Scientific). Since 198 1, more than 250,000 papers on semiconductor devices have been pub- lished, with numerous breakthroughs in device concepts and performances. The book clearly needed another major revision if it were to continue to serve its purpose. In this Third Edition of Physics of Semiconductor Devices, over 50% of the material has been revised or updated, and the material has been totally reorganized. We have retained the basic physics of classic devices and added many sections that are of con- temporary interest such as the three-dimensional MOSFETs, nonvolatile memory, modulation-doped field-effect transistor, single-electron transistor, resonant-tun- neling diode, insulated-gate bipolar transistor, quantum cascade laser, semiconductor sensors, and so on. On the other hand, we have omitted or reduced sections of less- important topics to maintain the overall book length. We have added a problem set at the end of each chapter. The problem set forms an integral part of the development of the topics, and some problems can be used as worked examples in the classroom. A complete set of detailed solutions to all end-of- chapter problems has been prepared. The solution manuals are available free to all adopting faculties. The figures and tables used in the text are also available, in elec- tronic format, to instructors from the publisher. Instructors can find out more informa- tion at the publisher’s website at http://ww.w iley.com/interscience/sze. V vi PREFACE In the course of writing this text, we had the fortune of help and support of many people. First we express our gratitude to the management of our academic and indus- trial institutions, the National Chiao Tung University, the National Nan0 Device Lab- oratories, Agere Systems, and MVC, without whose support this book could not have been written. We wish to thank the Spring Foundation of the National Chiao Tung University for the financial support. One of us (K. Ng) would like to thank J. Hwang and B. Leung for their continued encouragement and personal help. We have benefited greatly from suggestions made by our reviewers who took their time from their busy schedule. Credits are due to the following scholars: A. Alam, W. Anderson, S. Banerjee, J. Brews, H. C. Casey, Jr., P. Chow, N. de Rooij, H. Eisele, E. Kasper, S. Luryi, D. Monroe, P. Panayotatos, S. Pearton, E. F. Schubert, A. Seabaugh, M. Shur, Y. Taur, M. Teich, Y. Tsividis, R. Tung, E. Yang, and A. Zaslavsky. We also appreciate the permission granted to us from the respective journals and authors to reproduce their original figures cited in this work. It is our pleasure to acknowledge the help of many family members in preparing the manuscript in electronic format; Kyle Eng and Valerie Eng in scanning and importing text from the Second Edition, Vivian Eng in typing the equations, and Jen- nifer Tao in preparing the figures which have all been redrawn. We are further thankful to Norman Erdos for technical editing of the entire manuscript, and to Iris Lin and Nai-Hua Chang for preparing the problem sets and solution manual. At John Wiley and Sons, we wish to thank George Telecki who encouraged us to undertake the project. Finally, we are grateful to our wives, Therese Sze and Linda Ng, for their support and assistance during the course of the book project. S. M. Sze Hsinchu, Taiwan Kwok K. Ng San Jose, California July 2006 Contents Introduction 1 Part I Semiconductor Physics Chapter 1 Physics and Properties of Semiconductors-A Review 7 1.1 Introduction, 7 1.2 Crystal Structure, 8 1.3 Energy Bands and Energy Gap, 12 1.4 Carrier Concentration at Thermal Equilibrium, 16 1.5 Carrier-Transport Phenomena, 28 1.6 Phonon, Optical, and Thermal Properties, 50 1.7 Heterojunctions and Nanostructures, 56 1.8 Basic Equations and Examples, 62 Part I1 Device Building Blocks Chapter 2 p-n Junctions 79 2.1 Introduction, 79 2.2 Depletion Region, 80 2.3 Current-Voltage Characteristics, 90 2.4 Junction Breakdown, 102 2.5 Transient Behavior and Noise, 114 2.6 Terminal Functions, 118 2.7 Heterojunctions, 124 Chapter 3 Metal-Semiconductor Contacts 134 3. I Introduction, 134 3.2 Formation of Barrier, 135 3.3 Current Transport Processes, 153 3.4 Measurement of Barrier Height, 170 3.5 Device Structures, 181 3.6 Ohmic Contact, 187 Vii viii CONTENTS Chapter 4 Metal-Insulator-Semiconductor Capacitors 197 4.1 Introduction, 197 4.2 Ideal MIS Capacitor, 198 4.3 Silicon MOS Capacitor, 213 Part I11 Transistors Chapter 5 Bipolar Transistors 243 5.1 Introduction, 243 5.2 Static Characteristics, 244 5.3 Microwave Characteristics, 262 5.4 Related Device Structures, 275 5.5 Heterojunction Bipolar Transistor, 282 Chapter 6 MOSFETs 293 6.1 Introduction, 293 6.2 Basic Device Characteristics, 297 6.3 Nonuniform Doping and Buried-Channel Device, 320 6.4 Device Scaling and Short-Channel Effects, 328 6.5 MOSFET Structures, 339 6.6 Circuit Applications, 347 6.7 Nonvolatile Memory Devices, 350 6.8 Single-Electron Transistor, 360 Chapter 7 JFETs, MESFETs, and MODFETs 374 7.1 Introduction, 374 7.2 JFET and MESFET, 375 7.3 MODFET, 401 Part IV Negative-Resistance and Power Devices Chapter 8 Tunnel Devices 417 8.1 Introduction, 417 8.2 Tunnel Diode, 418 8.3 Related Tunnel Devices, 435 8.4 Resonant-Tunneling Diode, 454 Chapter 9 IMPATT Diodes 466 9.1 Introduction, 466 CONTENTS ix 9.2 Static Characteristics, 467 9.3 Dynamic Characteristics, 474 9.4 Power and Efficiency, 482 9.5 Noise Behavior, 489 9.6 Device Design and Performance, 493 9.7 BARITT Diode, 497 9.8 TUNNETT Diode, 504 Chapter 10 Transferred-Electron and Real-Space-Transfer Devices 510 10.1 Introduction, 5 10 10.2 Transferred-Electron Device, 5 11 10.3 Real-Space-Transfer Devices, 536 Chapter 11 Thyristors and Power Devices 548 11.1 Introduction, 548 11.2 Thyristor Characteristics, 549 11.3 Thyristor Variations, 574 11.4 Other Power Devices, 582 Part V Photonic Devices and Sensors Chapter 12 LEDs and Lasers 60 1 12.1 Introduction, 601 12.2 Radiative Transitions, 603 12.3 Light-Emitting Diode (LED), 608 12.4 Laser Physics, 621 12.5 Laser Operating Characteristics, 630 12.6 Specialty Lasers, 651 Chapter 13 Photodetectors and Solar Cells 663 13.1 Introduction, 663 13.2 Photoconductor, 667 13.3 Photodiodes, 671 13.4 Avalanche Photodiode, 683 13.5 Phototransistor, 694 13.6 Charge-Coupled Device (CCD), 697 13.7 Metal-Semiconductor-Metal Photodetector, 7 12 13.8 Quantum-Well Infrared Photodetector, 7 16 13.9 Solar Cell, 719 x CONTENTS Chapter 14 Sensors 743 14.1 Introduction, 743 14.2 Thermal Sensors, 744 14.3 Mechanical Sensors, 750 14.4 Magnetic Sensors, 758 14.5 Chemical Sensors, 765 Appendixes 773 A. List of Symbols, 775 B. International System of Units, 785 C. Unit Prefixes, 786 D. Greek Alphabet, 787 E. Physical Constants, 788 F. Properties of Important Semiconductors, 789 G. Properties of Si and GaAs, 790 H. Properties of SiO, and Si,N,, 791 Index 793