FORMATION AND CHARACTERIZATION OF OHMIC CONTACTS TO N-ALGAAS USING PDAUGE/AG/AU/

Sequential deposition of Pd/AuGe/Ag/Au and rapid thermal annealing at 450 to 550-degrees-C were employed to form a shallow ohmic contact to n-AlxGa1-xAs. Contact resistivity was in the range of (0.7-1) X 10(-5) at x = 0.3 to (2-4) X 10(-5) ohm-cm2 at x = 0.55. Limited interfacial reaction was verified by ion backscattering and x-ray diffraction tec hniques and attributed to the stability of Au-Ag solid solutions again st underlying substrates. Contacts form at 450 to 500-degrees-C, possi bly via solid-state reaction, whereas liquid phase reaction may take p lace at 550-degrees-C.