9.1 Introduction

You have bravely endured lengthy discussions on rather abstract and occasionally nebulous concepts in the hope that something more relevant to the practice of engineering will emerge. Well, here we are; at last we are going to discuss various semiconductor devices. It is impossible to include all of them, for there are so many nowadays. But if you follow carefully (and if everything we have discussed so far is at your fingertips) you will stand a good chance of understanding the operation of all existing devices and I would add you should be in a very good position to understand the operation of semiconductor devices to come in the near future. This is because human ingenuity has rather narrow limits. Hardly anyone ever produces a new idea. It is always some combination of old ideas that leads to reward. Revolutions are few and far between. It is steady progress that counts.