Electrical characteristics of high energy 120 Sn implantation in p-type GaAs Yousuf Pyar Ali a , A.M. Narsale b, * , B.M. Arora c , M.R. Gokhale c , D. Kanjilal d , V.P. Salvi e a Department of Physics, College of Education, Mukalla, Republic of Yemen b Department of Physics, University of Mumbai, Vidyanagari, Mumbai 400098, India c T. I. F. R., Homi Bhabha Road, Mumbai 400005, India d Nuclear Science Centre, Aruna Asaf Ali Marg, New Delhi 110067, India e B. N. N. College, Bhivandi, Thane 421305, India Abstract Single crystal p-GaAs substrates have been implanted at room temperature with 120 Sn ions at an energy of 70 MeV to a ¯uence of 1 ´ 10 14 ions/cm 2 . The implanted samples are annealed at dierent temperatures up to 850°C in hydrogen ambient. The resistance values are found to increase with increasing annealing temperature up to 550°C and then decrease for higher annealing temperatures. Low temperature resistance measurements of the samples annealed at 450°C indicate that the transport <200 K is dominated by variable range hopping conduction mechanism, whereas for the samples annealed at 550°C, the electrical conduction is due to hopping between the neighboring defect sites. The conduction mechanism for the samples annealed at 650°C is in the extended states at all temperatures but the behavior is similar to that due two acceptors partly compensated by a donor. On further annealing at 750°C the resistance of the sample is reduced further and the conduction mechanism is possibly due to carriers in the extended states governed by a single acceptor level, which is also responsible for the electrical conduction at room temperature and above, for the samples annealed at temperatures higher than 450°C. Ó 1999 Elsevier Science B.V. All rights reserved. PACS: 61.70.At; 61.70.Tm; 71.55.Eq; 72.80.Ey Keywords: MeV ion implantation; p-GaAs; Sn; Radiation defects 1. Introduction Ion implantation in GaAs has become a process of considerable technological importance in the development of device technology [1,2]. In recent years, high energy ion implantation has attracted considerable attention as a promising tool for the fabrication of special device structures which re- quire buried conducting or insulating layers [3]. However, the extension of the implantation energy to the MeV range raises an interesting question about the radiation-induced defects and their Nuclear Instruments and Methods in Physics Research B 156 (1999) 78±83 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +91-22-6528835; fax: +91-22- 6526250; e-mail: arun@physic.mu.ac.in 0168-583X/99/$ ± see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 9 9 ) 0 0 2 4 5 - 1