CHAPTER 1

Semiconductor Diodes

1.1  INTRODUCTION

It is now some 50 years since the first transistor was introduced on December 23, 1947. For those of us who experienced the change from glass envelope tubes to the solid-state era, it still seems like a few short years ago. The first edition of this text contained heavy coverage of tubes, with succeeding editions involving the important decision of
how much coverage should be dedicated to tubes and how much to semiconductor devices. It no longer seems valid to mention tubes at all or to compare the advantages of one over to other – we are firmly in the solid-state era.

The miniaturization that has resulted leaves us to wonder about its limits. Complete systems now appear on wafers thousands of time smaller than the single element of earlier networks. New designs and systems surface weekly. The engineer be comes more and more limited in his or her knowledge of the broad range of advances  - it is difficult enough simply to stay abreast of the changes in one area of research or development. We have also reached a point at which the primary purpose of the container is simply to provide some means to handling the device or system and to provide mechanism for attachment  to the remainder of the network. Miniaturization appears to be limited by three factors  (each of which will be addressed in this text ) : the quality of the semiconductor material itself, the network design technique, and the limits of the manufacturing and processing equipment.