Swift heavy ion irradiation of GaSb: From ion tracks to nanoporous networks

Ion track formation, amorphization, and the formation of porosity in crystalline GaSb induced by 185 MeV Au197 swift heavy ion irradiation is investigated as a function of fluence and irradiation angle relative to the surface normal. Rutherford backscattering spectrometry in channeling configuration and small-angle x-ray scattering reveal an ion track radius between 3 and 5 nm. The observed pore morphology and saturation swelling of GaSb films shows a strong irradiation angle dependence. Raman spectroscopy and scanning electron microscopy show that the ion tracks act as a source of strain in the material, leading to macroscopic plastic flow at high fluences and off-normal irradiation. The results are consistent with the ion hammering model for glasses. Furthermore, wide-angle x-ray scattering reveals the formation of nanocrystallites inside otherwise amorphous GaSb after the onset of porosity.