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

Abstract

57Fe Mössbauer 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 57 Mn ∗ ions are produced at the ISOLDE facility at CERN, ionized and accelerated to 60 keV energy and implanted with fluences of ⩽ 2 × 10 12 ion / cm 2 into single crystal samples. Mössbauer spectra were collected with a parallel plate avalanche counter. Analysis of the Mössbauer spectra required three components: an asymmetric doublet attributed to Fe atoms in implantation induced damaged environments, a single line assigned to Fe on substitutional In sites and a weak symmetric doublet assigned to impurity–vacancy complexes. In InP the substitutional Fe component ( Fe S ) becomes significant above 400 K; while in InAs the Fe S fraction is already appreciable (>30%) after implantation at room temperature. The asymmetric doublet dominates the spectra 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 Fe S component dominates the spectra at higher temperatures. There was no evidence of any magnetic components in the spectra, indicating that at the low concentrations used in our measurements, the Fe ions were predominantly in the Fe 2 + state.