Study of optical properties of swift heavy ion irradiated gallium antimonide S.K. Dubey a, * , R.L. Dubey a , A.D. Yadav a , V. Jadhav a , T.K. Gundu Rao b , T. Mohanty c , D. Kanjilal c a Department of Physics, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai 400 098, India b Regional Sophisticated Instrumentation Centre, IIT Bombay, Mumbai 400 076, India c Nuclear Science Centre, New Delhi 110 067, India Available online 4 January 2006 Abstract 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 h100i orientation were irradiated with 70 MeV 56 Fe ions at fluences varying from 1 · 10 12 to 1 · 10 14 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 irradia- tion-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 (x p ) was found to vary from 2.05 · 10 18 to 1.9 · 10 18 cm 3 . The samples annealed in vacuum (10 6 mb) over the temperature range 100–600 °C showed the significant damage recovery. Crown Copyright Ó 2005 Published by Elsevier B.V. All rights reserved. PACS: 61.72.V; 61.70.At Keywords: High-energy ion irradiation; Gallium antimonide; Iron; FTIR; Defects; Annealing 1. Introduction Gallium antimonide is a narrow band gap, III–V com- pound semiconductor and has received less attention as compared to some other III–V semiconductors such as GaAs and InP. Wiersma et al. have studied the tempera- ture dependent Hall effect and photoluminescence of car- bon-doped GaSb [1]. The positron lifetime spectroscopy studies of Zn-doped p-type GaSb showed the neutral V Ga -related defects [2] and these defects were annealed out at an annealing temperature of 300 °C. The optical measurement of hydrogen-passivated GaSb studies revealed that the passivation efficiency depends on the dop- ing concentration [3]. Su. et al. have reported the Raman spectra of GaSb samples irradiated with silicon ions at dif- ferent fluences varying from 1 · 10 13 to 1 · 10 15 ions cm 2 with different energies (70–150 keV) [4]. The complete recovery of damaged layer was found at 600 °C. To our knowledge, no work on very high energy (>10 MeV) iron ions irradiation in GaSb has been reported in the literature. In the present work, we have studied the Mid and far infra- red Fourier Transform characteristics of p-GaSb samples irradiated with 70 MeV 56 Fe 5+ ions at fluences of 1 · 10 12 ,1 · 10 13 and 1 · 10 14 ions cm 2 . 2. Experimental details The p-type GaSb of h100i orientation, 450 lm thick was used as substrate materials. These samples were cleaned 0168-583X/$ - see front matter Crown Copyright Ó 2005 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2005.11.131 * Corresponding author. Tel.: +91 22 26526250; fax: +91 22 26529780. E-mail address: skdubey@physics.mu.ac.in (S.K. Dubey). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 244 (2006) 141–144 NIM B Beam Interactions with Materials & Atoms