Integration of the Ni/InP system on a 300 mm platform for III-V/Si hybrid lasers

Abstract

The integration of III-V/Si hybrid lasers on a 300 mm platform for photonic applications requires the development of dedicated CMOS-compatible contacts, for which nickel-based ones are very good candidates. In this scope, this work presents and compares the impact of in situ preclean based on argon (Ar) or helium (He) plasma on the surface integrity of InP prior to the nickel (Ni) contact deposition. The resulting surface morphology, element distribution, phase formation sequence of the Ni/InP system, and electrical behavior of Ni/n-InP contacts are detailed using morphological, structural, and electrical characterizations. The results show that Ar preclean significantly damages the InP surface by generating high roughness and creating indium (In) dots on the top surface, while He preclean seems to induce lighter damages and no In dots. Although the phase sequence of the Ni/InP system is overall the same for each preclean, the electrical behavior differs depending on the nature of the preclean. On one hand, Ni/n-InP Ar-precleaned contacts exhibit nonohmic behavior for each investigated thermal budget. On the other hand, He-precleaned contacts features ohmic behavior for the as-deposited state and thermal anneals up to 350°C for 60 s. They, however, become nonohmic after anneals of 400 and 450°C for 60 s. These results, hence, suggest that the difference of electrical behavior obtained between Ar and He-precleaned Ni/n-InP contacts is due to differences in the state surface and morphology.