Preparation and semiconductive properties of rock salt type solid solution systems,Cd1?xMxS (M = Sr, Ca, Mg, Pb, Sn)

Measurements have been made of the semiconductive properties of rock salt type solid solution systems, Cd_1?xM_xS (M = Sr, Ca, Mg, Pb, Sn) synthezised at high pressures. The Cd_1?xCa_xS system has a high electrical resistivity of more than 3 × 10¹⁰Ω-cm, and a band gap estimated from its optical absorption edge which varies from 1.9–2.6 eV with Cd_1?xPb_xS system is between 1 and 10Ω-cm, and decreases with increase in the substitution ratio. This system is photoconductive, similar to the normal pressure phase of CdS, and the photoconductivity peak shifts from 0.75–0.96μm with increase in the substitution ratio from 0.1–0.5. The above results are extrapolated to pure CdS and give for CdS having a rock salt type structure high resistivity, photoconductivity, and a band gap of 1.7–1.8 eV at room temperature and normal pressure.