Microdefect Studies of Fe-Doped Semi-Insulating Inp

Different microdefects have been identified in Fe-doped semi-insulating InP: i) very small defects located on dislocations, ii) relatively large precipitates embedded in the matrix, surrounded by a spherical volume depleted of iron, iii) large inclusions in the heavily doped crystal tails. Investigations of these defects by Photoetching, Scanning Photoluminescence, SEM and TEM suggest that: i) the large inclusions are due to incorporation of second-phase particles (FeP, FeP2) which form in the melt as it becomes very rich in iron, ii) the matrix precipitates are possibly the result of iron gathering around a collection point, iii) the small defects are different, in nature, from those containing iron and thought to be either very small precipitates or microloops.