The Dependence of Photoetching n ‐ InP on Surface Preparation and Electrolyte Metal Ion Impurities

Photochemical etching of n‐InP using an Ar+ laser and dilute phosphoric acid was studied as a function of surface preparation. The samples were prepared by chemical polishing with a 1% bromine‐methanol solution and mechanical polishing with alumina powders. The surfaces were characterized using electron microscopy, photoluminescence, and mechanical stylus profiling. Photoetch rate was found to increase with surface roughness. The variation of photoetch rate with polishing powder size and morphology was due to the increased effective surface area associated with rougher surfaces. Samples with similar effective surface areas had similar photoetch rates irrespective of their surface treatment. Samples photoetched in solutions having a copper concentration ≥2×10−4 molar and samples with gold wire bonded to them had photoetch rates 2–5 times larger than those without copper in solution. Both zinc and magnesium in solution did not enhance photoetch rates.