Some Optical Properties of Cadmium Sulfide Containing Phosphorus and Arsenic

Ion implantation and sputtering have generated renewed interest in the possibility of obtaining p-type CdS. However, little is known concerning the properties of acceptors. In an attempt to learn something about acceptors in CdS, phosphorus- and arsenic-doped samples have been prepared by diffusion in a saturated Cd atmosphere at 800°C for 24 h. The electrical and optical properties of the doped samples are compared with undoped test samples (fired in saturated Cd atmosphere but without added dopant). The electrical properties indicate only a slight compensation due to the presence of P and As. The optical studies (photoluminescence, photoconductivity, and optical absorption) yield a level about 1-eV above the valence band, which is presumably the binding energy of an electron to a compensated P or As acceptor.