LOW-RESISTANCE PD GE OHMIC CONTACTS TO EPITAXIALLY LIFTED-OFF N-TYPE GAAS FILM/

A low resistance PdGe nonalloyed ohmic contact has been successfully f ormed to epitaxially lifted-off n-type GaAs films. The contact is made by lifting off partially metallized n-type GaAs films using the epita xial lift-off method and bonding them to metallized Si substrates by n atural intermolecular Van Der Waals forces. Low temperature sintering (200 degrees C) of this contact results in metallurgical bonding and f ormation of the ohmic contact. We have measured specific contact resis tances of 5 x 10(-5) Ohm-cm(2) which is almost half the value obtained for pure Pd contacts. Germanium forms a degenerately doped heterojunc tion interfacial layer to GaAs. Our experimental results show that ger manium diffuses to the interface and acts as a dopant layer to n-GaAs film surface. Therefore, for epitaxially lifted-off n-type GaAs films, PdGe is a low resistance ohmic metal contact to use.