Revealing of defects in InP by shallow (submicron) photoetching

Abstract
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.