Revealing of defects in InP by shallow (submicron) photoetching

Indium phosphide samples (n and p type) have been photoetched in solutions consisting of CrO3-HF-H2O, i. e., in diluted Sirtl or Sirtl-like mixtures under laser or white light illumination. The method proved to be very sensitive for the delineation of defects and inhomogeneities in substrates and epitaxial layers. In n-type InP an etch depth of 0.05–0.3 μm is sufficient to reveal dislocations, growth striations, precipitates, and linear defects or to delineate epijunctions in cross sections. In p-type material, removal of 0.5–1 μm is required to obtain a clear picture of the defects. In contrast to n-type material the results for p-type InP are similar with and without illumination. The method has been calibrated with Huber etch.