We investigated structural properties of polycrystalline SiGe grown by directional growth method for solar cells. The average Ge composition was systematically changed in the range between 0 and 10 at%. Distributions of concentration and crystallographic orientation in the SiGe crystal were measured and the preferential growth orientation was found to change from (1 1 1) to (1 1 0) with increasing average Ge composition. Misfit dislocation was observed using transmission electron microscope. There was few dislocations in SiGe crystals when the average Ge composition was between 0 and 5 at% though a lot of dislocations existed at the average Ge composition of 10 at%. We concluded that the optimum Ge composition is around 5 at% for solar cells.
ASJC Scopus subject areas