Effect of Ge-related mechanical strain on defect and impurity behaviour in ion-implanted silicon

Abstract

Silicon substrates were implanted with 320 and 640 keV G e + ions at doses up to 3 X 10 16 c m -2 , corresponding to a Ge peak concentration of ~ 3 at.%, and annealed at 1050°C. The interactions between the mechanical strain caused by Ge atoms on silicon sites and impurities and radiation defects induced by subsequent H + and B + ion implantation have been investigated. Mechanical strain, radiation defects and impurity behaviour were studied by means of X-ray, DLTS, and electrical measurements. Under the influence of mechanical strain we observed in H + -implanted samples a decrease of the defect concentration and a decrease of the annealing temperature of implantation defects. In B + -implanted samples the Ge-related strain promotes the transition of B atoms into substitutional positions. The effect of the mechanical strain field on the diffusion of vacancy defects and impurity atoms is discussed.