57 Fe Mössbauer studies on 57 Mn ⁄ implanted InP and InAs

Fe Mossbauer spectroscopy studies, following implantation of radioactive 57 Mn � , have been conducted on InP and n- and p-type InAs at temperatures above 300 K. The 57Mnions are produced at the ISOLDE facility at CERN, ionized and accelerated to 60 keV energy and implanted with fluences of 6 2 � 10 12 ion=cm2 into single crystal samples. Mossbauer spectra were collected with a parallel plate ava- lanche counter. Analysis of the Mossbauer spectra required three components: an asymmetric doublet attributed to Fe atoms in implantation induced damaged environments, a single line assigned to Fe on sub- stitutional In sites and a weak symmetric doublet assigned to impurity-vacancy complexes. In InP the sub- stitutional Fe component ðFeSÞ becomes significant above 400 K; while in InAs the FeS fraction is already appreciable (>30%) after implantation at room temperature. The asymmetric doublet dominates the spec- tra of all samples but shows significant reduction in intensity with increasing temperatures. The radiation damage shows strong annealing above 400 K in the InAs samples and above 450 K in InP; the Fe-defect complex dissociates at 500 K, and the FeS component dominates the spectra at higher temperatures. There was no evidence of any magnetic components in the spectra, indicating that at the low concentra- tions used in our measurements, the Fe ions were predominantly in the Fe 2þ state.