Cfo. Graeff et al., SPIN-DEPENDENT PHOTOCONDUCTIVITY IN HYDROGENATED AMORPHOUS-SILICON GERMANIUM ALLOYS, Journal of non-crystalline solids, 166, 1993, pp. 15-18
We use spin-dependent photo-conductivity (SDPC) to study the recombina
tion process of photo-excited carriers in hydrogenated amorphous silic
on germanium alloys (a-SixGe1-x:H). The incorporation of Ge is marked
by a sudden change in the SDPC signal ( -Delta sigma/sigma ) from (a-S
i:H)-like to (a-Ge:H)-like. The Ge atoms create new states which domin
ate transport and recombination of photo-created free carriers. In par
ticular, the SDPC lineshape analysis indicates that the a-Si:H conduct
ion band tail is affected by alloying with small concentrations of ger
manium.