METALLURGY FOR OHMIC CONTACTS TO P-TYPE GaAs
Original Publication Date: 1988-Jun-01
Included in the Prior Art Database: 2005-Feb-15
Proposed is a process for the fabrication of low resistance ohmic contacts to p-type GaAs involving the formation of a shallow high doping concentration at the metal-semiconductor interface. After applying a metal compound (e.g., GePt) and on subsequent heat treatment, a replacement mechanism takes place causing the As to out-diffuse, leaving As vacancies which are then occupied by the Ge atoms that provide for the p-type doping. In the process, after cleaning of the GaAs surface where the contact is to be provided, a GePt layer of uncritical thickness is evaporated. It may, thereafter, be covered with a layer of Au which serves to reduce the sheet resistance of the contact film but has no part in the actual formation of the contact.