Anodizable metallic contacts to mercury cadmium telleride

Claim 1

A semiconductor device comprising a compound semiconductor material consisting essentially of (Hg,Cd)Te, a metallic contact attached thereto, a uniform passivating native semiconductor oxide layer adjacent said metallic contact and a surface of said compound semiconductor material, the otherwise exposed surface of said semiconductor material being anodically oxidizable to form said passivating native semiconductor oxide layer thereon, said metallic contact comprising a plurality of metal layers including: (a) a contact metal layer formed on a surface portion of said semiconductor material, said contact metal layer forming a substantially non-rectifying contact with said semiconductor material and providing a diffusion barrier and comprising a metal selected from the group consisting of titanium, chromium, nickel and palladium; (b) a top metal layer formed so as to overlie said metal layers, the exposed surface portion of said top metal layer being anodically oxidizable to form a metal oxide thereon and thereby prevent any significant interference by said metal layers with the substantially uniform formation of said passivating native semiconductor oxide, said top metal layer being selected from the group consisting of metals occupying a position between hydrogen and magnesium in the Electromotive Series; and (c) an oxide layer formed on said top metal layer, the thickness of said oxide layer being sufficient to substantially prevent any interference by said metallic contact with the anodic oxidation of said compound semiconductor material at any time subsequent to the formation of said oxide layer.