The Doppler broadening spectrum of a wafer was measured using a variable-energy positron beam to investigate the effects of vacancy-type defects introduced by 180keV Ar ion implantation. The S-parameter in the damaged layer decreased with annealing temperature up to 673K, and then increased from 673 to 1373K. At annealing temperatures ranging from ambient to 673K, argon-decorated vacancies were formed by argon atoms combining with open-volume defects at inactive positron sites. With further increase of annealing temperature, argon-decorated vacancies dissociate and subsequently migrate and coalesce, leading to an increase of S-parameter. Furthermore, the buried vacancy-layer became narrow with increasing annealing temperature. At 1373K, the buried vacancy-layer moved towards the sample surface.

The Formation and Evolution of Vacancy-Type Defects in Ar-Implanted Silicon Studied by Slow-Positron Annihilation Spectroscopy. B.S.Li, C.H.Zhang, Y.R.Zhong, D.N.Wang, L.H.Zhou, Y.T.Yang, H.H.Zhang, L.Q.Zhang: Nuclear Instruments and Methods in Physics Research B, 2009, 267[14], 2395-8