Growth of high quality cSiGe p-n double layers for high-efficiency solar cells

We have grown silicon-germanium alloys and p-n junctions of high crystal quality on Si substrates by LPE from Bi, Ga, and In solutions at temperatures between 300 and 920/spl deg/C. The layer thicknesses ranged from 1 nm to 100 /spl mu/m. Doping levels from 1/spl times/10/sup 16/ to 4/spl times/10/sup 19/ cm/sup -3/ were obtainable by using Ga and As as dopants. The carrier mobility values reached 50% of the upper theoretical limit. Average dislocation densities were below 5/spl times/10/sup 8/ cm/sup -2/, even for Ge on Si. Growth rates above 60 nm/sec were for example achieved on 4" substrates. Layers grown from In solution gave us the best data for photovoltaic applications.