Interfacial point defects in heavily implanted silicon germanium alloys

Abstract

Comparing electron paramagnetic resonance (EPR) spectra from samples of two different alloy compositions we develop a structural model for SG1, a Ge dangling bond defect in O implanted SiGe. Analysis of the angular dependence of EPR spectra from measurements of 10% and 40% Ge alloys reveals that in both cases the defect exhibits 〈111〉 symmetry of the Si lattice; however, the defect in the 40% alloy exhibits a larger g⊥ and broader linewidth than the defect in the 10% alloys. From these observations we propose that for both alloy compositions SG1 is a trivalently bonded Ge atom, and we suggest that the center in the 40% Ge alloy involves a greater number of Ge backbonds than the center in 10% Ge samples. That implantation with Ne does not produce SG1 provides evidence to suggest that the defect is located at interfaces between the SiGe alloy and SiO2 precipitates formed by oxygen implantation.