High-resolution luminescence studies of indium phosphide under ohmic contacts

Cathodoluminescence (CL) has been used to investigate the nature of n-type InP directly underneath AuGeNi ohmic contacts subjected to various heat treatments. The study of this contact system by CL has shown directly that the quality of the underlying InP is significantly modified up to distances of several microns from the contact interface. These changes are brought about by the interaction of the contact components with the semiconductor. Contrary to the widely accepted view, no evidence of n+ doping of the InP by Ge was observed in any of the contacts examined. Possible explanations for the observed reduction in CL efficiency obtained from the InP close to the contact interface are discussed.