The di-vacancy was known to introduce 3 energy levels in the energy-band gap of Si. Using deep level transient spectroscopy on particle-irradiated p+n and n+p diodes, these levels were monitored in epitaxially grown, strain-relaxed Si1-xGex for x-values of 0 to 0.5. Both the single- and double-acceptor levels located in the upper half of the band gap in Si move gradually deeper into the gap with increasing x. While the double-acceptor level remains in the upper half of the band gap of the alloys, the single-acceptor level crosses the mid-gap for an x-value of about 0.25. The donor level became gradually more shallow, but remains pinned to the conduction band. The anneal temperature of the di-vacancy was found to be independent of composition in the investigated composition range.

The Di-Vacancy in Particle-Irradiated, Strain-Relaxed SiGe. H.Av Skardi, A.Bro Hansen, A.Mesli, A.Nylandsted Larsen: Nuclear Instruments and Methods in Physics Research B, 2002, 186[1-4], 195-200