Heteroepitaxy of GaAs, GaP and InP on Si By Omvpe and Their Application to thin Film Solar Cells

Abstract

AbstractOrganometallic vapor phase epitaxial (OMVPE) growth of GaAs, GaP and InP on Si has been studied using the two-step growth method. Growth parameters for a heteroepitaxial film with a specular surface, a single-domain structure and high crystallinity are demonstrated and discussed. Residual strains in grown films are evaluated and analyzed by taking account of elastic lattice deformation due to lattice mismatch or thermally- induced strain accomodation by rearrangement of misfit dislocations. Thin film GaAs and InP solar cells are fabricated and their performances are discussed in relation to defect density in the films. For GaAs cells, an efficiency of 18 % (AM1.5, active area) is attained by reducing defect density to 2×106 >cm−2 . The defect density is ~. 5×107 cm−2 in the present InP films, and is needed to be less than 106 cm−2 to attain an efficiency of 18 %.