Book Preface

Philosophy and Goals
The purpose of the third edition of this book is to provide a basis for understanding the characteristics, operation, and limitations of semiconductor devices. In order to gain this understanding, it is essential to have a thorough knowledge of the physics of the semiconductor material. The goal of this book is to bring together quantum mechanics, the quantum theory of solids, semiconductor material physics, and semiconductor device physics. All of these components are vital to the understanding of both the operation of present day devices and any future development in the field.

The amount of physics presented in this text is greater than what is covered in many introductory semiconductor device books. Although this coverage is more extensive, the author has found that once the basic introductory and material physics have been thoroughly covered, the physics of the semiconductor device follows quite naturally and can be covered fairly quickly and efficiently. The emphasis on the underlying physics will also be a benefit in understanding and perhaps in developing new semiconductor devices.

Since the objective of this text is to provide an introduction to the theory of semiconductor devices, there is a great deal of advanced theory that is not considered. In addition, fabrication processes are not described in detail. There are a few references and general discussions about processing techniques such as diffusion and ion implantation, but only where the results of this processing have direct impact on device characteristics.

Prerequisites
This book is intended for junior and senior undergraduates. The prerequisites for understanding the material are college mathematics, up to and including differential equations, and college physics, including an introduction to modern physics and electrostatics. Prior completion of an introductory course in electronic circuits is helpful, but not essential.

Organization
The text begins with the introductory physics, moves on to the semiconductor material physics, and then covers the physics of semiconductor devices. Chapter 1 presents an introduction to the crystal structure of solids, leading to the ideal single-crystal semiconductor material. Chapters 2 and 3 introduce quantum mechanics and the quantum theory of solids, which together provide the necessary basic physics.

Chapters 4 through 6 cover the semiconductor material physics. Chapter 4 presents the physics of the semiconductor in thermal equilibrium; Chapter 5 treats the transport phenomena of the charge carriers in a semiconductor. The nonequilibrium excess carrier characteristics are then developed in Chapter 6. Understanding the behavior of excess carriers in a semiconductor is vital to the goal of understanding the device physics.

The physics of the basic semiconductor devices is developed in Chapters 7 through 13. Chapter 7 treats the electrostatics of the basic pn junction, and Chapter 8 covers the current-voltage characteristics of the pn junction. Metal-semiconductor junctions, both rectifying and nonrectifying, and semiconductor heterojunctions are considered in Chapter 9, while Chapter 10 treats the bipolar transistor. The physics of the metal-oxide-semiconductor field-effect transistor is presented in Chapters 11 and 12, and Chapter 13 covers the junction field-effect transistor. Once the physics of the pn junction is developed, the chapters dealing with the three basic transistors may be covered in any order––these chapters are written so as not to depend on one another. Chapter 14 considers optical devices and finally Chapter 15 covers power semiconductor devices.

Use of the Book
The text is intended for a one-semester course at the junior or senior level. As with most textbooks, there is more material than can be conveniently covered in one semester; this allows each instructor some flexibility in designing the course to his/her own specific needs. Two possible orders of presentation are discussed later in a separate section in this preface. However, the text is not an encyclopedia. Sections in each chapter that can be skipped without loss of continuity are identified by an asterisk in both the table of contents and in the chapter itself. These sections, although important to the development of semiconductor device physics, can be postponed to a later time.

The material in the text has been used extensively in a course that is required for junior-level electrical engineering students at the University of New Mexico. Slightly less than half of the semester is devoted to the first six chapters; the remainder of the semester is devoted to the pn junction, the bipolar transistor, and the metal-oxide-semiconductor field-effect transistor. A few other special topics may be briefly considered near the end of the semester.

Although the bipolar transistor is discussed in Chapter 10 before the MOSFET or JFET, each chapter dealing with one of the three basic types of transistors is written to stand alone. Any one of the transistor types may be covered first.

Notes to the Reader
This book introduces the physics of semiconductor materials and devices. Although many electrical engineering students are more comfortable building electronic circuits or writing computer programs than studying the underlying principles of semiconductor devices, the material presented here is vital to an understanding of the limitations of electronic devices, such as the microprocessor.

Mathematics is used extensively throughout the book. This may at times seem tedious, but the end result is an understanding that will not otherwise occur. Although some of the mathematical models used to describe physical processes may seem abstract, they have withstood the test of time in their ability to describe and predict these physical processes.

The reader is encouraged to continually refer to the preview sections so that the objective of the chapter and the purposes of each topic can be kept in mind. This constant review is especially important in the first five chapters, dealing with basic physics.

The reader must keep in mind that, although some sections may be skipped without loss of continuity, many instructors will choose to cover these topics. The fact that sections are marked with an asterisk does not minimize the importance of these subjects.

It is also important that the reader keep in mind that there may be questions still unanswered at the end of a course. Although the author dislikes the phrase, “it can be shown that ,’’ there are some concepts used here that rely on derivations beyond the scope of the text. This book is intended as an introduction to the subject. Those questions remaining unanswered at the end of the course, the reader is encouraged to keep “in a desk drawer.’’ Then, during the next course in this area of concentration, the reader can take out these questions and search for the answers.

Order of Presentation
Each instructor has a personal preference for the order in which the course material is presented. Listed below are two possible scenarios. The first case, called the classical approach, covers the bipolar transistor before the MOS transistor. However, because the MOS transistor topic is left until the end of the semester, time constraints may shortchange the amount of class time devoted to this important topic.

The second method of presentation listed, called the nonclassical approach, discusses the MOS transistor before the bipolar transistor. Two advantages to this approach are that the MOS transistor will not get shortchanged in terms of time devoted to the topic and, since a “real device” is discussed earlier in the semester, the reader may have more motivation to continue studying this course material. A possible disadvantage to this approach is that the reader may be somewhat intimidated by jumping from Chapter 7 to Chapter 11. However, the material in Chapters 11 and 12 is written so that this jump can be made.

Unfortunately, because of time constraints, every topic in every chapter cannot be covered in a one-semester course. The remaining topics must be left for a second-semester course or for further study by the reader.

Features of the Third Edition
Preview section: A preview section introduces each chapter. This preview links the chapter to previous chapters and states the chapter’s goals, i.e., what the reader should gain from the chapter.

Examples: An extensive number of worked examples are used throughout the text to reinforce the theoretical concepts being developed. These examples contain all the details of the analysis or design, so the reader does not have to fill in missing steps.

Test your understanding: Exercise or drill problems are included throughout each chapter. These problems are generally placed immediately after an example problem, rather than at the end of a long section, so that readers can immediately test their understanding of the material just covered. Answers are given for each drill problem so readers do not have to search for an answer at the end of the book. These exercise problems will reinforce readers’ grasp of the material before they move on to the next section.

Summary section: A summary section, in bullet form, follows the text of each chapter. This section summarizes the overall results derived in the chapter and reviews the basic concepts developed.

Glossary of important terms: A glossary of important terms follows the Summary section of each chapter. This section defines and summarizes the most important terms discussed in the chapter.

Checkpoint: A checkpoint section follows the Glossary section. This section states the goals that should have been met and states the abilities the reader should have gained. The Checkpoints will help assess progress before moving on to the next chapter.

Review questions: A list of review questions is included at the end of each chapter. These questions serve as a self-test to help the reader determine how well the concepts developed in the chapter have been mastered.

End-of-chapter problems: A large number of problems are given at the end of each chapter, organized according to the subject of each section in the chapter body. A larger number of problems have been included than in the second edition. Design-oriented or open-ended problems are included at the end in a Summary and Review section.

Computer simulation: Computer simulation problems are included in many end-of-chapter problems. Computer simulation has not been directly incorporated into the text. However, a website has been established that considers computer simulation using MATLAB. This website contains computer simulations of material considered in most chapters. These computer simulations enhance the theoretical material presented. There also are exercise or drill problems that a reader may consider.

Reading list: A reading list finishes up each chapter. The references, that are at an advanced level compared with that of this text, are indicated by an asterisk.

Answers to selected problems: Answers to selected problems are given in the last appendix. Knowing the answer to a problem is an aid and a reinforcement in problem solving.

Solutions Manual available to instructors in paper form and on the website.

Power Point slides of important figures are available on the website.

Computer simulations are available on the website.

Acknowledgments
I am indebted to the many students I have had over the years who have helped in the evolution of the third edition as well as the first and second editions of this text. I am grateful for their enthusiasm and constructive criticism. The University of New Mexico has my appreciation for providing an atmosphere conducive to writing this book.,

I want to thank the many people at McGraw-Hill, for their tremendous support. A special thanks to Kelley Butcher, senior developmental editor. Her attention to details and her enthusiasm throughout the project are especially recognized and appreciated. I also appreciate the efforts of Joyce Watters, project manager, who guided the work through its final phase toward publication.

The following reviewers deserve thanks for their constructive criticism and suggestions for the third edition of this text.

Thomas Mantei, University of Cincinnati
Cheng Hsiao Wu, University of Missouri—Rolla

Kazutoshi Najita, University of Hawaii at Manoa

John Naber, University of Louisville

Gerald Oleszek, University of Colorado—Colorado Springs

Marc Cahay, University of Cincinnati

The following reviewers deserve thanks for their constructive criticism and suggestions for the second edition:

Jon M. Meese, University of Missouri—Columbia

Jacob B. Khurgin, Johns Hopkins University

Hong Koo Kim, University of Pittsburgh

Gerald M. Oleszek, University of Colorado—Colorado Springs

Ronald J. Roedel, Arizona State University

Leon McCaughan, University of Wisconsin

A. Anil Kumar, Prairie View A & M University

Since the third edition is an outgrowth of the first edition of the text, the following reviewers of the first edition deserve my continued thanks for their thorough reviews and valuable suggestions:

Timothy J. Drummond, Sandia Laboratories

J. L. Davidson, Vanderbilt University

Robert Jackson, University of Massachusetts—Amherst

C. H. Wu, University of Missouri—Rolla

D. K. Reinhard, Michigan State University

Len Trombetta, University of Houston

Dan Moore, Virginia Polytechnic Institute and State University

Bruce P. Johnson, University of Nevada—Reno

William Wilson, Rice University

Dennis Polla, University of Minnesota

G. E. Stillman, University of Illinois—Urbana-Champaign

Richard C. Jaeger, Auburn University

Anand Kulkarni, Michigan Technological University

Ronald D. Schrimpf, University of Arizona