Semiconductor Physics and Devices Basic Principles Fourth Edition PDF

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Semiconductor Physics and Devices Basic Principles Fourth Edition Donald A. Neamen University of New Mexico TM 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...

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Semiconductor Physics and Devices Basic Principles Fourth Edition

Donald A. Neamen University of New Mexico

TM

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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. Previous editions © 2003, 1997 and 1992. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of The McGraw-Hill Companies, Inc., including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. Some ancillaries, including electronic and print components, may not be available to customers outside the United States. This book is printed on acid-free paper. 1 2 3 4 5 6 7 8 9 0 DOC/DOC 1 0 9 8 7 6 5 4 3 2 1 ISBN MHID

978-0-07-352958-5 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. Neamen. — 4th ed. p. cm. Includes index. ISBN 978-0-07-352958-5 (alk. paper) 1. Semiconductors. I. Title. QC611.N39 2011 537.6'22—dc22 2010045765

www.mhhe.com

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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.D. 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 department. 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 graduating 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.

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CONTENTS

Preface

x

2.2

Prologue—Semiconductors and the Integrated Circuit xvii

PART

I—Semiconductor Material Properties

CHAPTER

2.2.1 2.2.2 2.2.3

2.3

1

Preview 1 Semiconductor Materials Types of Solids 2 Space Lattices 3 1.3.1 1.3.2 1.3.3 1.3.4

1.4 1.5 *1.6

2.4

Primitive and Unit Cell 3 Basic Crystal Structures 4 Crystal Planes and Miller Indices 6 Directions in Crystals 9

The Diamond Structure 10 Atomic Bonding 12 Imperfections and Impurities in Solids 1.6.1 1.6.2

*1.7

1

14

Imperfections in Solids 14 Impurities in Solids 16

Growth of Semiconductor Materials

17

1.7.1 Growth from a Melt 17 1.7.2 Epitaxial Growth 19

1.8

3.0 3.1

Preview 58 Allowed and Forbidden Energy Bands

59

Electrical Conduction in Solids

72

3.2.1 The Energy Band and the Bond Model 72 3.2.2 Drift Current 74 3.2.3 Electron Effective Mass 75 3.2.4 Concept of the Hole 78 3.2.5 Metals, Insulators, and Semiconductors 80

Introduction to Quantum Mechanics 25

2.1.1 Energy Quanta 26 2.1.2 Wave–Particle Duality 27 2.1.3 The Uncertainty Principle 30

3

3.1.1 Formation of Energy Bands 59 *3.1.2 The Kronig–Penney Model 63 3.1.3 The k-Space Diagram 67

2

Preview 25 Principles of Quantum Mechanics

Summary 51 Problems 52

Introduction to the Quantum Theory of Solids 58

3.2

2.0 2.1

The One-Electron Atom 46 The Periodic Table 50

CHAPTER

Summary 20 Problems 21

CHAPTER

Electron in Free Space 35 The Infinite Potential Well 36 The Step Potential Function 39 The Potential Barrier and Tunneling 44

Extensions of the Wave Theory to Atoms 46 2.4.1 2.4.2

2.5

31

The Wave Equation 31 Physical Meaning of the Wave Function 32 Boundary Conditions 33

Applications of Schrodinger’s Wave Equation 34 2.3.1 2.3.2 2.3.3 2.3.4

The Crystal Structure of Solids 1 1.0 1.1 1.2 1.3

Schrodinger’s Wave Equation

26 3.3

Extension to Three Dimensions 3.3.1 3.3.2

83

The k-Space Diagrams of Si and GaAs 83 Additional Effective Mass Concepts 85

iv

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Contents

3.4

Density of States Function

4.7

85

3.4.1 Mathematical Derivation 85 3.4.2 Extension to Semiconductors 88

3.5

Statistical Mechanics

91

3.6

4

Preview 106 Charge Carriers in Semiconductors 4.1.1 4.1.2 4.1.3 4.1.4

4.2

107

Equilibrium Distribution of Electrons and Holes 107 The n0 and p0 Equations 109 The Intrinsic Carrier Concentration 113 The Intrinsic Fermi-Level Position 116

Dopant Atoms and Energy Levels

The Extrinsic Semiconductor

123

4.3.1

Equilibrium Distribution of Electrons and Holes 123 4.3.2 The n0 p0 Product 127 *4.3.3 The Fermi–Dirac Integral 128 4.3.4 Degenerate and Nondegenerate Semiconductors 130

4.4

5.2

5.3

Statistics of Donors and Acceptors

131

Charge Neutrality

135

*5.4 5.5

4.6

Position of Fermi Energy Level

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Graded Impurity Distribution

176

Induced Electric Field 176 The Einstein Relation 178

The Hall Effect 180 Summary 183 Problems 184

6

Nonequilibrium Excess Carriers in Semiconductors 192 6.0 6.1

Preview 192 Carrier Generation and Recombination 6.1.1 6.1.2

6.2

198

6.2.1 Continuity Equations 198 6.2.2 Time-Dependent Diffusion Equations

Ambipolar Transport 6.3.1 6.3.2 6.3.3 6.3.4 *6.3.5

193

The Semiconductor in Equilibrium 193 Excess Carrier Generation and Recombination 194

Characteristics of Excess Carriers

141

4.6.1 Mathematical Derivation 142 4.6.2 Variation of EF with Doping Concentration and Temperature 144 4.6.3 Relevance of the Fermi Energy 145

172

Diffusion Current Density 172 Total Current Density 175

CHAPTER

6.3

4.5.1 Compensated Semiconductors 135 4.5.2 Equilibrium Electron and Hole Concentrations 136

Carrier Diffusion

5.3.1 5.3.2

4.4.1 Probability Function 131 4.4.2 Complete Ionization and Freeze-Out 132

4.5

Preview 156 Carrier Drift 157

5.2.1 5.2.2

118

4.2.1 Qualitative Description 118 4.2.2 Ionization Energy 120 4.2.3 Group III–V Semiconductors 122

4.3

5.0 5.1

5.1.1 Drift Current Density 157 5.1.2 Mobility Effects 159 5.1.3 Conductivity 164 5.1.4 Velocity Saturation 169

The Semiconductor in Equilibrium 106 4.0 4.1

5

Carrier Transport Phenomena 156

Summary 98 Problems 100

CHAPTER

Summary 147 Problems 149

CHAPTER

3.5.1 Statistical Laws 91 3.5.2 The Fermi–Dirac Probability Function 91 3.5.3 The Distribution Function and the Fermi Energy 93

v

199

201

Derivation of the Ambipolar Transport Equation 201 Limits of Extrinsic Doping and Low Injection 203 Applications of the Ambipolar Transport Equation 206 Dielectric Relaxation Time Constant 214 Haynes–Shockley Experiment 216

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vi

6.4 *6.5

Contents

6.5.1 6.5.2

*6.6

8.1.4 Minority Carrier Distribution 283 8.1.5 Ideal pn Junction Current 286 8.1.6 Summary of Physics 290 8.1.7 Temperature Effects 292 8.1.8 The “Short” Diode 293

Quasi-Fermi Energy Levels 219 Excess Carrier Lifetime 221 Shockley–Read–Hall Theory of Recombination 221 Limits of Extrinsic Doping and Low Injection 225

Surface Effects

8.2

227

6.6.1 Surface States 227 6.6.2 Surface Recombination Velocity 229

6.7

Summary 231 Problems 233

PART

8.2.1 Generation–Recombination Currents 296 8.2.2 High-Level Injection 302

8.3

*8.4

7

Preview 241 Basic Structure of the pn Junction Zero Applied Bias 243

242

7.2.1 Built-in Potential Barrier 243 7.2.2 Electric Field 246 7.2.3 Space Charge Width 249

7.3

Reverse Applied Bias

251

7.3.1 Space Charge Width and Electric Field 251 7.3.2 Junction Capacitance 254 7.3.3 One-Sided Junctions 256

7.4 *7.5

Junction Breakdown 258 Nonuniformly Doped Junctions

*8.5 8.6

CHAPTER

9.0 9.1

9.2

8.1.1

9.3 277

Qualitative Description of Charge Flow in a pn Junction 277 8.1.2 Ideal Current–Voltage Relationship 278 8.1.3 Boundary Conditions 279

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318

9

Preview 331 The Schottky Barrier Diode

332

Metal–Semiconductor Ohmic Contacts

349

9.2.1 Ideal Nonrectifying Barrier 349 9.2.2 Tunneling Barrier 351 9.2.3 Specific Contact Resistance 352

8

Preview 276 pn Junction Current

The Tunnel Diode Summary 321 Problems 323

9.1.1 Qualitative Characteristics 332 9.1.2 Ideal Junction Properties 334 9.1.3 Nonideal Effects on the Barrier Height 338 9.1.4 Current–Voltage Relationship 342 9.1.5 Comparison of the Schottky Barrier Diode and the pn Junction Diode 345

The pn Junction Diode 276 8.0 8.1

314

Metal–Semiconductor and Semiconductor Heterojunctions 331

262

Summary 267 Problems 269

304

The Turn-off Transient 315 The Turn-on Transient 317

CHAPTER

7.5.1 Linearly Graded Junctions 263 7.5.2 Hyperabrupt Junctions 265

7.6

Charge Storage and Diode Transients 8.4.1 8.4.2

The pn Junction 241 7.0 7.1 7.2

Small-Signal Model of the pn Junction 8.3.1 Diffusion Resistance 305 8.3.2 Small-Signal Admittance 306 8.3.3 Equivalent Circuit 313

II—Fundamental Semiconductor Devices

CHAPTER

Generation–Recombination Currents and High-Injection Levels 295

Heterojunctions 9.3.1 9.3.2 9.3.3 *9.3.4 *9.3.5

354

Heterojunction Materials 354 Energy-Band Diagrams 354 Two-Dimensional Electron Gas 356 Equilibrium Electrostatics 358 Current–Voltage Characteristics 363

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Contents

9.4

11.1.2 Channel Length Modulation 446 11.1.3 Mobility Variation 450 11.1.4 Velocity Saturation 452 11.1.5 Ballistic Transport 453

Summary 363 Problems 365

CHAPTER

10

Fundamentals of the Metal–Oxide– Semiconductor Field-Effect Transistor 371 10.0 10.1

Preview 371 The Two-Terminal MOS Structure

Capacitance–Voltage Characteristics

The Basic MOSFET Operation

Frequency Limitations 10.4.1 10.4.2

*10.5 10.6

11.4

CHAPTER

394

422

Additional Electrical Characteristics

Radiation and Hot-Electron Effects 11.5.1 11.5.2 11.5.3

11.6

464

475

Radiation-Induced Oxide Charge 475 Radiation-Induced Interface States 478 Hot-Electron Charging Effects 480

Summary 481 Problems 483

CHAPTER

12

The Bipolar Transistor 491 12.0 12.1

Preview 491 The Bipolar Transistor Action 12.1.1 12.1.2

427

12.1.3 12.1.4

12.2

492

The Basic Principle of Operation 493 Simplified Transistor Current Relation— Qualitative Discussion 495 The Modes of Operation 498 Amplification with Bipolar Transistors 500

Minority Carrier Distribution

501

12.2.1 Forward-Active Mode 502 12.2.2 Other Modes of Operation 508

11

Preview 443 Nonideal Effects

444

11.1.1 Subthreshold Conduction 444

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*11.5

403

Metal–Oxide–Semiconductor Field-Effect Transistor: Additional Concepts 443 11.0 11.1

457

11.4.1 Breakdown Voltage 464 *11.4.2 The Lightly Doped Drain Transistor 470 11.4.3 Threshold Adjustment by Ion Implantation 472

Small-Signal Equivalent Circuit 422 Frequency Limitation Factors and Cutoff Frequency 425

The CMOS Technology Summary 430 Problems 433

Threshold Voltage Modifications 11.3.1 Short-Channel Effects 457 11.3.2 Narrow-Channel Effects 461

10.3.1 MOSFET Structures 403 10.3.2 Current–Voltage Relationship—Concepts 404 *10.3.3 Current–Voltage Relationship— Mathematical Derivation 410 10.3.4 Transconductance 418 10.3.5 Substrate Bias Effects 419

10.4

MOSFET Scaling 455 11.2.1 Constant-Field Scaling 455 11.2.2 Threshold Voltage—First Approximation 456 11.2.3 Generalized Scaling 457

11.3

10.2.1 Ideal C–V Characteristics 394 10.2.2 Frequency Effects 399 10.2.3 Fixed Oxide and Interface Charge Effects 400

10.3

11.2

372

10.1.1 Energy-Band Diagrams 372 10.1.2 Depletion Layer Thickness 376 10.1.3 Surface Charge Density 380 10.1.4 Work Function Differences 382 10.1.5 Flat-Band Voltage 385 10.1.6 Threshold Voltage 388

10.2

vii

12.3

Transistor Currents and Low-Frequency Common-Base Current Gain 509 12.3.1 12.3.2

Current Gain—Contributing Factors 509 Derivation of Transistor Current Components and Current Gain Factors 512

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viii

Contents

12.3.3 12.3.4

12.4

Nonideal Effects 12.4.1 12.4.2 12.4.3 12.4.4 *12.4.5 12.4.6

12.5

Summary 517 Example Calculations of the Gain Factors 517

*13.3

13.3.1 13.3.2 13.3.3

522

Base Width Modulation 522 High Injection 524 Emitter Bandgap Narrowing 526 Current Crowding 528 Nonuniform Base Doping 530 Breakdown Voltage 531

Equivalent Circuit Models

*13.4

*13.5

536

Frequency Limitations

12.7

Large-Signal Switching

13.6

549

Other Bipolar Transistor Structures

551

552

14.0 14.1

14.2.3 14.2.4 14.2.5

13.1.1 13.1.2

13.2

14.3

572

The Device Characteristics

578

13.2.1

Internal Pinchoff Voltage, Pinchoff Voltage, and Drain-to-Source Saturation Voltage 578 13.2.2 Ideal DC Current–Voltage Relationship— Depletion Mode JFET 582 13.2.3 Transconductance 587 13.2.4 The MESFET 588

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14.4

619

624

The pn Junction Solar Cell 624 Conversion Efficiency and Solar Concentration 627 Nonuniform Absorption Effects 628 The Heterojunction Solar Cell 629 Amorphous Silicon Solar Cells 630

Photodetectors 14.3.1 14.3.2 14.3.3 14.3.4 14.3.5

Basic pn JFET Operation 572 Basic MESFET Operation 576

618

Photon Absorption Coefficient 619 Electron–Hole Pair Generation Rate 622

Solar Cells 14.2.1 14.2.2

13

Preview 571 JFET Concepts

14

Preview 618 Optical Absorption 14.1.1 14.1.2

The Junction Field-Effect Transistor 571 13.0 13.1

III—Specialized Semiconductor Devices

Optical Devices

14.2

Summary 558 Problems 560

CHAPTER

602

Summary 609 Problems 611

CHAPTER

12.8.1 Polysilicon Emitter BJT 552 12.8.2 Silicon–Germanium Base Transistor 554 12.8.3 Heterojunction Bipolar Transistors 556

12.9

High Electron Mobility Transistor

PART

546

12.7.1 Switching Characteristics 549 12.7.2 The Schottky-Clamped Transistor

*12.8

Small-Signal Equivalent Circuit 598 Frequency Limitation Factors and Cutoff Frequency 600

13.5.1 Quantum Well Structures 603 13.5.2 Transistor Performance 604

545

12.6.1 Time-Delay Factors 545 12.6.2 Transistor Cutoff Frequency

593

Channel Length Modulation 594 Velocity Saturation Effects 596 Subthreshold and Gate Current Effects 596

Equivalent Circuit and Frequency Limitations 598 13.4.1 13.4.2

*12.5.1 Ebers–Moll Model 537 12.5.2 Gummel–Poon Model 540 12.5.3 Hybrid-Pi Model 541

12.6

Nonideal Effects

633

Photoconductor 633 Photodiode 635 PIN Photodiode 640 Avalanche Photodiode 641 Phototransistor 642

Photoluminescence and Electroluminescence 643 14.4.1 Basic Transitions 644 14.4.2 Luminescent Efficiency 645 14.4.3 Materials 646

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Contents

14.5

Light Emitting Diodes

14.6

Laser Diodes

654

15.7

Summary 701 Problems 703

APPENDIX

14.6.1

Stimulated Emission and Populatio...