Chapter 9 Photoconduction in III-V Compounds

Abstract

This chapter discusses the application of photoconduction in III–V compounds—indium antimonide, indium arsenide, indium phosphide, aluminium antimonide, aluminium arsenide, aluminium phosphide, gallium antimonide, gallium arsenide, and gallium phosphide. The basic process of photoconductivity is the production of “free” charge carriers in a semiconductor by optical excitation. In the simplest case of an intrinsic semiconductor, optical excitation raises electrons to the conduction band where they are free to conduct and at the same time leaves holes in the valence band, which further add to the conductivity. In an impure semiconductor, in addition to the intrinsic effect that will still be present, it is possible to excite electrons from a bound state at donor levels into the conduction band. Equally, in a p -type semiconductor, electrons can be excited from the valence band to acceptor centers, leaving mobile holes. In both cases of impurity photoconductivity, only one type of free carrier is produced.