Study of ohmic multilayer metal contacts to p-type ZnSe

A novel approach for making ohmic contacts to p-type ZnSe has been introduc ed. This approach includes growth of p-ZnSe at low temperature by a variant of molecular beam epitaxy, then treating the surface with KOH solution, fo llowed by deposition of a Te/Pd/Pt/Au metal layer and annealing at 200-250 degrees C for 5 min. As a result, a stable ohmic contact up to a current de nsity of 2 kA cm(-2) was obtained. Using this contact fabrication procedure , a ZnSe-based quantum-well laser was demonstrated in Continuous wave mode of operation at room temperature. The formation of the ohmic contact is sug gested to be due to the presence of oxygen on the ZnSe surface, the creatio n of TeO2 at the metal/ZnSe interface, and the diffusion of Pd into ZnSe. ( C) 1999 American Vacuum Society. [S0734-2101(99)01102-1].