Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

Abstract

Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 100〉 orientations and ∼500μm thick p-type GaSb samples with carrier concentration of 3.30×1017cm−3 were irradiated at 100MeV Fe7+ ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5×1010–1×1014 ions cm−2. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1×1013, 5×1013 and 1×1014 ions cm−2, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1×1013 ion cm−2 was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617nm represent the high energy GaSb; E1, E1+Δ and E2 band gaps in all irradiated samples.