Generation–Recombination and Diffusion Noise in Cadmium Sulphide Photoconductors

Abstract

Noise in CdS stemming from generation–recombination, trapping, diffusion, and drift is investigated. In the treatment, the transport equations corresponding to a four‐level model are considered. Closed form expressions for the various parts of the spectrum and for the pertinent relaxation times are given. Experimental results demonstrated many features of the computed spectra, particularly for absorption in the long‐wavelength tail. Some quantitative values for the rate constants and effective diffusion constants are derived. The relative variance of the spectra, <ΔN²>/N₀ is found to be close to unity.