Studies of defects and annealing behavior of silicon irradiated with 70 MeV 56 Fe ions S.K. Dubey a, * , A.D. Yadav a , B.K. Kamalapurkar a , T.K. Gundu Rao b , M. Gokhale c , T. Mohanty d , D. Kanjilal d a Department of Physics, University of Mumbai, Vidyanagari Campus, Mumbai 400 098, India b Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Mumbai 400 076, India c Tata Institute of Fundamental Research, Mumbai 400 005, India d Nuclear Science Centre, New Delhi 110 067, India Available online 10 January 2006 Abstract The effects of 70 MeV irradiation of iron ions in p-type silicon at fluences between 1 · 10 12 and 5 · 10 14 ions cm 2 were investigated by high resolution X-ray diffraction (HRXRD), electron spin resonance (ESR) and current–voltage measurements. The irradiated samples were isochronally annealed in nitrogen ambient up to 973 K for 2 min using the rapid thermal annealing (RTA) system. The screw dis- location density of the annealed sample (5 · 10 14 ions cm 2 ) estimated at each stage of annealing from the broadening of the HRXRD peak was observed to change from 8.70 · 10 7 to 1.58 · 10 7 cm 2 with increasing temperatures. The strain and stress parameters estimated at each stage of annealing using the FWHM of x-scan clearly indicate relative trend towards the un-irradiated silicon sample. The elec- tron spin resonance studies indicate the presence of the dangling bond state of silicon (Si„Si) and complex defects. The annealing at 873 K was found to be sufficient for complete removal of the defect centers induced due to irradiation. The I–V studies performed on the irradiated samples before and after annealing indicate that the defects created as a consequence of irradiation trap the charge carriers. Ó 2005 Elsevier B.V. All rights reserved. PACS: 61.72.H; 61.72.Dd Keywords: High energy irradiation; Silicon; Iron ions; HRXRD; ESR; Current–voltage; Defects; Annealing 1. Introduction The irradiation of solids with MeV energy leads to the transfer of the energy to the target atoms of the order of keV/A ˚ mostly due to electronic excitations. The energy thus deposited causes various modifications in the materi- als. In addition, it also creates different types of complex defects e.g. broken bonds, voids, screw dislocations, edge dislocations, divacancies, etc. Some important aspects of these defects are still not well understood. In recent years, several studies have been conducted in silicon irradiated with different ions i.e. Ni. Au, Si, H, He, O, Ag, Ge, Sn, etc. [1–7] at high energy (in MeV energy range). However the irradiation of silicon with high-energy Fe ions has not been reported in the literature. The optical studies of crystalline germanium and silicon bombarded at 60– 75 MeV Ni ions with fluences varying from 1 · 10 13 to 1 · 10 15 ions cm 2 in the fundamental absorption and interband transition regions showed the change in the refractive index, extinction coefficient and fundamental absorption [1]. Damage induced by 90 MeV silicon ions with fluences ranging from 1.25 to 5 · 10 14 cm 2 in silicon have been studied by grazing angle X-ray diffraction, reflec- tion of UV–visible radiation and lifetime of minority carri- ers [2]. Deep level transient spectroscopy (DLTS) was used 0168-583X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2005.11.031 * Corresponding author. Tel.: +91 22 2652 6250; fax: +91 22 2652 9780. 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) 157–160 NIM B Beam Interactions with Materials & Atoms