SiGe layer structures for solar cell application grown by liquid phase epitaxy

Si/sub 1-x/Ge/sub x/ layers with x=0.09-0.27 were grown on Si (111) substrates by liquid phase epitaxy (LPE). The formation of dislocations caused by the lattice mismatch was reduced from 5/spl times/10/sup 7/ to 7/spl times/10/sup 5/ cm/sup -2/ by growing buffer layers in which the Ge content increased continuously from 4 at% Ge at the substrate/buffer interface up to the Ge content of the Si/sub 1-x/Ge/sub x/ base layer. The p-type SiGe layers grown from indium solution are about 20 /spl mu/m thick. The carrier concentration of 5/spl times/10/sup 16/-2/spl times/10/sup 17/ cm/sup -3/ depends on Ge content and Ga doping. With a thin-film cell processed from a 14 /spl mu/m thick LPE-grown Si/sub 0.9/Ge/sub 0.1/ base layer, an efficiency of 9.1% was achieved even without the presence of a buffer layer.