Deep-level transient spectroscopic studies were made of 2MeV proton-induced defect electronic levels in strained epitaxial Si1-xGex layers, where x ranged from 0 to 0.13. It was found that the bombardment resulted in the formation of a predominant peak in the deep level transient spectra for all compositions. Isochronal 1200s annealing studies of the observed deep level revealed that the peak annealed out at 100 to 200C. This peak was associated with VP pairs. The compositional dependence of the activation enthalpy of the VP pair was non-linear, with a sharp increase at x = 0.04 and little variation at higher Ge concentrations. After annealing the VP pair, the predominant defect level was attributed to the single acceptor state of the divacancy [V2(-/0)]. The double-acceptor state [V2(=/-)] was strongly suppressed in the strained layers. The compositional dependence of the activation enthalpy of V2(-/0) was relatively weak; with a small decrease in the activation enthalpy. It was found that the formation of V2 in the strained layers was enhanced with respect to that in Si. This was associated with an increased concentration of vacancies in the strained layer; which acted as a sink for vacancies migrating in the substrate.

Vacancy-Related Deep Levels in n-Type SiGe Strained Layers. E.V.Monakhov, A.Y.Kuznetsov, B.G.Svensson: Physical Review B, 2001, 63[24], 245322 (7pp)