Generation of vacancy cluster-related defects during single MeV silicon ion implantation of silicon

Abstract

Deep Level Transient Spectroscopy (DLTS) has been used to study defects formed in bulk silicon after implantation of 8.3MeV 28Si3+ ions at room temperature. For this study, Schottky diodes prepared from n-type Czohralski-grown silicon wafers have been implanted in the single ion regime up to fluence value of 1×1010cm−2 utilizing the scanning focused ion microbeam as implantation tool and the Ion Beam Induced Current (IBIC) technique for ion counting.Differential DLTS analysis of the vacancy-rich region in self-implanted silicon reveals a formation of the broad vacancy-related defect state(s) at Ec −0.4eV. Direct measurements of the electron capture kinetics associated with this trap at Ec −0.4eV, prior to any annealing do not show an exponential behaviour typical for the simple point-like defects. The logarithmic capture kinetics is in accordance with the theory of majority carrier capture at extended or cluster-related defects. We have detected formation of two deep electron traps at Ec −0.56eV and Ec −0.61eV in the interstitial-rich region of the self-implanted silicon, before any annealing. No DLTS signal originating from vacancy-oxygen trap at Ec −0.17eV, present in the sample irradiated with 0.8MeV neutrons, has been recorded in the self-implanted sample.