Structural and compositional analysis of GaSb nanofoams obtained by ion irradiation of sputtered films

Here we show the formation of GaSb nanofoams by ion irradiation of sputter-deposited GaSb films and a comprehensive characterization of its structural and compositional properties. Polycrystalline GaSb films deposited on SiO2/Si substrates were irradiated with 16 MeV Au+7 ions, in the fluence range 1 × 1012–3 × 1014 cm−2, and the structural and compositional changes induced by ion irradiation were characterized by Rutherford backscattering spectrometry, scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and x-ray absorption fine structure analyses. We demonstrate that GaSb films deposited by magnetron sputtering at 400 °C are polycrystalline, with zincblende phase, and ion irradiation induces increasing disorder for irradiation fluences up to 1 × 1013 cm−2, beyond which the films become amorphous. At 1 × 1014 cm−2, porosity reaches significant levels, contributing to the increase in GaO bonding throughout the film, accompanied by a decrease in GaSb bonding as well as an expansion in the GaSb bond length, consistent with the increase in effective surface area due to the formation of nanometric foams. The first few nanometres close to the surface exhibit only GaO bonding, even for polycrystalline films, in addition to SbSb and SbO. The GaO component at the surface shows high irradiation resistance, while ion irradiation favors SbSb bonding in expense of SbO bonding.