In1-xGaxSb nanofoams made by ion irradiation of sputtered films: Atomic composition and structure

Abstract

This article reports on the atomic composition and structural changes induced by ion irradiation in In1-xGaxSb films deposited by magnetron sputtering on SiO2/Si. Samples with x values equal 0, 0.2, 0.4, 0.5 and 1 were irradiated with 16 MeV Au+7 ions, in the fluence range 5 × 1013–2 × 1014 cm−2 (3 × 1014 for GaSb) and the structure and atomic composition of the films were investigated. Upon irradiation, all films attain a nanofoam-like structure, and the most pronounced swelling was observed in ternary films with 20% Ga atomic concentration. With particle induced x-ray emission technique, we identified the presence of C, O, Ga, In and Sb, with C and O concentrations significantly higher in the nanofoams, compared to the as-deposited films. Rutherford backscattering spectrometry analysis showed the atomic composition of the ternaries is not uniform, but forms two layers with slightly different relative atomic concentrations, specially after irradiation, with C and O uptake greatly enhanced by ion irradiation, more pronounced towards the surface. Grazing incidence x-ray diffraction analysis revealed that ion irradiation with total fluence of 2 × 1014 cm−2 induces amorphization of the ternaries, except for samples with 50% Ga, which remain polycrystalline, despite the ion-induced porosity.