Solid State Electronic Devices, 7th Edition

4.3 Carrier Lifetime and Photoconductivity

When excess electrons and holes are created in a semiconductor, there is a corresponding increase in the conductivity of the sample as indicated by Eq. (3–​43). If the excess carriers arise from optical luminescence, the resulting increase in conductivity is called photoconductivity. This is an important effect, with useful applications in the analysis of semiconductor materials and in the operation of several types of devices. In this section we shall examine the mechanisms by which excess electrons and holes recombine and apply the recombination kinetics to the analysis of photoconductive devices. However, the importance of recombination is not limited to cases in which the excess carriers are created ...