Abstract: A method of manufacturing a semiconductor device having an improved ohmic contact system to epitaxially grown, low bandgap compound semiconductors. In an exemplary embodiment, the improved ohmic contact system comprises a thin reactive layer of nickel deposited on a portion of an epitaxially grown N+ doped InGaAs emitter cap layer. The improved ohmic contact system further comprises a thick refractory layer of titanium or other suitable material deposited on the thin reactive layer. Both the reactive layer and the refractory layer are substantially free of gold and other low resistivity, high conductivity metal overlayers.

Abstract: A method of manufacturing a semiconductor device having an improved ohmic contact system. The improved ohmic contact system comprises a thin reactive layer of platinum deposited on a portion of the base layer. The improved ohmic contact system further comprises a thick refractory layer of titanium or other suitable material deposited on the thin reactive layer. Both the reactive layer and the refractory layer are substantially free of gold. The improved ohmic contact system and method for forming the same eliminate base contact punchthrough on high performance semiconductor devices, such as heterojunction bipolar transistors, minimize raw material costs, and decrease manufacturing costs.