Optical absorption and transmission in CuZnS alloys

Abstract

Varieties of pellets of the alloy of copper (Cu) and zinc sulphide (ZnS) have been produced by pressing mechanically together fine ground powders of Cu and ZnS alloys prepared by the chemical reaction between the aqueous solution of copper II nitrate trihydrate (Cu(NO₃)₂.3H₂O) and ZnS powder. The optical absorption and transmission in these alloys were investigated in the spectral range 200nm –750nm at room temperature to examine their potential for use in optoelectronic devices. The investigation showed that the alloys are transparent over the ultraviolet (UV) spectrum but with increasing dopant mole fraction the absorption edge moves into the visible region. However, a gradual decrease in the energy gaps of the samples with a corresponding gradual shift in the absorption edge towards the visible spectrum, as the concentration of the copper impurity increases leads to an improvement in conductivity of the alloys examined. The location of the band gaps of CuZnS alloys (3.58 – 3.82eV) within the UV spectrum suggests that all the samples are very valuable in optoelectronic devices that utilize wide band gap materials.