Material Science and Metallurgy

18

Semiconductors

18.1 INTRODUCTION

Semiconductor devices, the electronic components made of semiconductor materials, are essential in modern-day electrical equipments, from computer to cellular phone to digital audio players. A semiconductor is a solid, whose electrical properties can be controlled over a wide range. Silicon is the most commercially exploited semiconductor.

The intrinsic electrical properties of a semiconductor can be permanently modified by introducing controlled quantities of impurity atoms. This process is called ‘doping’.

In many semiconductors, when electrons fall from the conductor band to the valence band, they often emit light, i.e. photoemission e.g. a light-emitting diode (LED).

This chapter studies the behaviour ...