Surface analyses combined with barrier-height studies indicate that Cu2O Schottky barriers made with low-work-function metals (Yb, Mg, and Mn) are essentially Cu/Cu2O cells due to reduction of the Cu2O surface and subsequent interdiffusion phenomena. The copper-rich region essentially determines the barrier height. As a result, efficiencies of Cu2O Schottky-barrier solar cells are usually less than 1%. It is concluded that to achieve significant increases in Cu2O cell efficiencies, MIS or heterojunction device structures must be utilized.

Conductive crystalline films of ZnS have been deposited by coevaporating ZnS and Al, or In. As-deposited conductive films have been obtained on occasion. Conductive films are consistently obtained with heat treatment subsequent to deposition. Typically, film resistivities are in the range 1–10 Ω cm. Hall mobilities on the order of 775 cm2 V−1 sec−1 have been measured. The results reported here suggest that with improved control of deposition parameters, conductive crystalline ZnS films can be obtained (as deposited) with two-source thermal evaporation.