Amorphous phase formation in ion implanted In x Ga 1- x As

Abstract

The amorphisation kinetics of InxGa1-xAs alloys were investigated using Rutherford backscattering spectrometry in channelling configuration. Using metal organic chemical vapour deposition, epitaxial InxGa1-xAs layers were grown on either GaAs, InP or InAs over a wide range of stoichiometries. Ion implantation was then performed using 60 keV Ge ions at room temperature. In contrast with AlxGa1-xAs alloys, InxGa1-xAs does not exhibit amorphisation kinetics intermediate between the two binary extremes. The amorphisation behaviour was fit using the Hecking model yielding a determination of the relative probabilities of direct impact amorphisation (Pa) and stimulated amorphisation (As). For InxGa1-xAs, Pa is effectively independent of the stoichiometry whilst As exhibits a quadratic dependence on x with a maximum at x ≈ 0.31 (where the critical ion fluence for amorphisation is at a minimum). We attribute the rapid InxGa1-xAs amorphisation to the local strain induced by a bimodal bond length distribution, the latter demonstrated by previous EXAFS studies. Show more