A reproducible ohmic contact to n-type GaAs0.6P0.4

A study is reported on several alternate metal systems based upon AuGeNiCr, which provide reproducibly $\text{～10}{}^{\mathrm{?4}}\text{Ω-}\text{cm}{}^2$ specific contact resistance to n-type GaAs_0.6P_0.4, employing the conventional open-tube sintering furnace. A simple metallurgical model is presented to explain the success of this technique. It is found that a thin chromium-oxide film is formed during the heat treatment, which is thought to prevent metal pads from balling-up, and volatile components of the semiconductor from evaporating. In this way, the metal-semiconductor interface re-growth process is optimized to consistently provide low resistance ohmic contacts.