The effect of strain and composition upon deep electronic levels in the energy band gap of epitaxial Si0.87Ge0.13 layers, grown by chemical vapour deposition, was investigated by using deep level transient spectroscopy. Two major levels, which were attributed to a vacancy-P pair and a singly negative divacancy, were observed. It was found that the VP and V2(-/0) exhibited opposite dependences upon Ge composition. Thus, the activation enthalpy of VP increased with respect to pure Si while that of V2(-/0) decreased. The apparent intensity of the VP level was observed to decrease in Si0.87Ge0.13 layers, with respect to that in Si, while the formation of V2 was enhanced during annealing at temperatures above about 100C.

Comparative Study of Divacancy and E-Center Electronic Levels in Si and Strained SiGe Layers E.V.Monakhov, A.Y.Kuznetsov, B.G.Svensson: Journal of Applied Physics, 2000, 87[9], 4629-31