TRANSPORT-PROPERTIES OF LOW-RESISTANCE OHMIC CONTACTS TO INP

The transport properties of conventional Au-based low-resistance ohmic contacts to n- and p-type InP have been investigated. For n-type InP, a good agreement between the minimum specific contact resistance and the bulk doping density is observed in accordance with an inverse bulk doping density dependence for the specific contact reistance. Drift a nd diffusion across a thermodynamically stable metalphosphide-InP junc tion is found to be the rate-limiting step of the low-resistance conta cts to n-type InP. Tunneling is not observed, but rather a significant ly effective Schottky barrier lowering is initially responsible for th e low-resistance contacts. Significant Schottky barrier lowering is al so observed for ohmic contacts to p-type InP, but no total transition from predominately thermionic emission to drift and diffusion is obser ved for low-resistance contacts to p-type InP, indicating that the con tacts are not fully developed, and that further reduction of the speci fic contact resistance can be expected.