Electrically active defects due to end-of-ion-range damage in silicon irradiated with MeV Ar+ ions

TLDR: In this article, the authors reported the occurrence of mid-gap acceptor levels using DLTS and TATS in a region well beyond the ion range, indicating that these deep levels are associated with point defects with local disorder in the neighbourhood.

Abstract: Damage induced by MeV Ar+ ion implantation and end of range defects in Si have been studied by capacitance-voltage, thermally stimulated capacitance, deep level transient spectroscopy (DLTS) and time analyzed transient spectroscopy (TATS). Unlike earlier studies, which focus on defects induced during post-implantation annealing steps, we study as-implanted p-type silicon samples. We report the occurrence of mid-gap acceptor levels using DLTS and TATS in a region well beyond the ion range. The presence of temperature dependent series resistance due to damaged region distorts DLTS lineshapes, even leading to sign reversal of DLTS peaks in some cases. A new and better method of correcting series resistance effects in capacitance transients has been employed. It is based on detecting the point of inversion of isothermal transients which are nonmonotonic due to the presence of series resistance. The capture process is found to be thermally activated with a high barrier energy. Possible origin of capture barrier and broadening in activation energy are discussed. Our results indicate that these deep levels are associated with point defects with local disorder in the neighbourhood.