A Channeling Study on Mg Implanted InSb Single Crystals
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A CHANNELING STUDY ON Mg IMPLANTED InSb SINGLE CRYSTALS
H.W. ALBERTS Department of Physics,
University of Pretoria, Pretoria, South Africa
ABSTRACT Proton and a-particle channeling were used to study the radiation damage caused by the implantation of 160 keV Mg ions in InSb. The implantations took place at various substrate temperatures ranging from room temperature to temperatures just below the melting point and doses ranging 16 2 from 5.1013 to 1.10 Mg+ cM- . The isochronal annealing of the room temperature implanted crystals started at 200 C and damage could not be completely removed even at temperatures just below the melting point. For crystals implanted at elevated substrate temperatures no annealing 0 effects during implantation occured up to 400 C. Above 4000C a sharp reduction of damage indicates that the rate of formation of more complex defect configurations during the implantation process becomes smaller than the annihilation rate of the vacancy-interstitial pairs. A nonlinear dependence exists between the degree of radiation damage in the InSb lattice and the implanted dose.
INTRODUCTION Laser annealing techniques can be applied to obtain improved electrical properties of InSb devices [1-3]. However, information about radiation defects in ion-irradiated InSb is important because radiation defects exert a strong influence on the properties of the implanted layers. Therefore, the radiation damage produced in InSb single crystals has been studied for awide variety of bombarding particles at different energies. The radiation damage due to electron beam irradiation was the most extensively studied [4, 5 and other references therein] and seems to be well understood. Studies were also performed with light particles where the radiation damage is stable at room temperature. It has been reported that p-type InSb can be converted by irradiation with protons [6, 7] and neutrons [8] ton-type. The radiation damage produced in InSb at liquid nitrogen temperature with 0 9 MeV [9] and 12 MeV [10] deuterons seems to anneal below 150 C. Since He +-particles are normally used as an analyzing beam in RBS and channeling techniques [11-15] it is of utmost importance to know what structural changes may be introduced by these particles in order to avoid misinterBogatyrev and Kachurin [7] implanted 300 keV He+ pretation of the results. ions at room temperature and found that n-type InSb was formed after anneal2 ing for doses _ 1014cM . Bogatyrev et. al [16] implanted 300 keV He+ ions at elevated substrate temperatures and found that when the irradiation temperature did not exceed 2000C, subsequent isochronous annealing (up to 4000C) produced n-type layers and no evidence of amorphization was found. However, when the substrate temperature was higher than 250 C no n-type layers were formed. Also Chernysheva et. al [21] found no evidence of amorphizationafter 300 keV implants at room temperature. Friedland et. al [15] implanted 50 keV 0 a-particles at 200, 200 and 2500C as well as 2 MeV particles at room temperature. For both
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