Semiconductor Basics

Introduction

A couple of years ago, I was asked to give a talk to the Rotary club in Terrassa, a city about 20 miles northwest of Barcelona. They asked me to divide the talk into three parts: 15 minutes biographical, 15 minutes on my technical work, and 15 minutes about NASA. The first and last 15 minutes of the talk went well, but the technical explanation about how infrared detectors work was disappointing. Yes, they did understand the uses and applications of infrared detectors, my technical work with the astronomical observatories of NASA, but the explanation on how infrared detectors work was not as clear and instructive as I had hoped. I was then and I am now convinced that any educated person can understand how semiconductor devices work. This talk two years ago was my motivation to start writing this book.

Semiconductors are the basis for almost all modern electronic devices. For many people semiconductors are a mysterious material that somehow has taken over modern electronics. In the same way that we understand the concept of god and creatures, but semi‐gods are confusing, most of us have an idea of what a conductor (electricity flows through it) and an insulator (it doesn’t) are, but what the heck is a semiconductor? Furthermore, the prevalent material used for fabricating semiconductors is pure silicon, the second most common element found on earth (28%) after oxygen (47%). Why not use aluminum, the next common element (8%), or strontium or some other exotic and ...