Study of optical properties of swift heavy ion irradiated gallium antimonide

Gallium antimonide (GaSb) which is a narrow band gap compound semiconductor has received attention because of its potential applications in optoelectronic devices. In the present work, p-type GaSb wafers of 〈1 0 0〉 orientation were irradiated with 70 MeV 56Fe ions at fluences varying from 1 × 1012 to 1 × 1014 ions cm−2. Mid-infrared and Far-infrared Fourier Transform (FT) measurements were carried out to investigate the optical properties of as irradiated and vacuum annealed samples. Mid-infrared Fourier Transform study revealed that the optical absorption of the irradiated samples increases with increasing ion fluence due to increase in irradiation-induced defects. The band gap energy determined from the infrared spectra was found to change from 0.65 to 0.62 eV while for non-irradiated GaSb wafer the corresponding estimate was 0.67 eV. The density of the carrier estimated from the plasma frequency (ωp) was found to vary from 2.05 × 1018 to 1.9 × 1018 cm−3. The samples annealed in vacuum (10−6 mb) over the temperature range 100–600 °C showed the significant damage recovery.