Photocapacitance studies of CdS:Cu

Abstract

Schottky diodes of copper doped CdS have been studied using photocapacitance techniques. Copper doping of CdS gives rise to deep hole states in the lower half of the band gap. The binding energies of the ground state and excited state are 1.1 and 0.34 eV, respectively. Optical emission of both holes and electrons as well as internal transitions followed by thermal emission of holes have been studied and absolute values of photoionization cross sections have been measured. The results are related to previous measurements of luminescence, absorption, photoconductivity, and photo-Hall effect. A model for the electronic structure of the dominant copper related center is discussed.