Electroless Ni as a Refractory Ohmic Contact for n ‐ InP

Abstract

We report on the realization of ohmic contacts for using Ni electroless deposition. A nickel film can be deposited by two wet methods: first, noncatalytically, to obtain a 100 nm Ni film, and now, catalytically, which avoids activating the contact. Catalytic deposition starts when a small sheet of Ni is laid on the substrate and the autocatalytic deposition goes on. The contact reactions to annealing treatment in junctions also are reported. Chemical depth profiling by Auger electron spectroscopy, low incidence x‐ray diffraction, and scanning electron microscopy (SEM) are used to study the morphology and the structure of the nickel films. Just after deposition, only compound is detected: this phase and interphase evolve with the annealing temperature to ternary and binary phases. The value of the specific contact resistance is in the annealing temperature range 350°C. This value does not evolve with high annealing temperatures and is held even after an annealing treatment at 400°C for 20 h or 500°C for 3 h conferring to this ohmic contact a refractory quality.