Growth and Characterization of CuInSe2Epitaxial Films for Device Applications

Abstract

AbstractCuInSe2(CIS) epitaxial layers have been grown on both GaAs (001) and In0.29Ga0.71As pseudo lattice-matched substrates by molecular beam epitaxy, and characterized for device applications. Despite a large lattice mismatch of Δa/a˜2.2%, epitaxial growth of CuInSe2has been demonstrated on GaAs (001) showing their film properties strongly dependent on the Cu/In ratio. In-rich films had a large number of twins on {112} planes, and were found to be heavily compensated. On the other hand, Cu-rich films showed distinct photoluminescence emissions indicating significantly higher film quality in comparison with In-rich films. Two dimensional reciprocal x-ray intensity area mapping and cross-sectional transmission electron microscopy showed the formation of an interfacial layer in the vicinity of the CuInSe2/GaAs interface resulting from the strain-induced interdiffusion between CuInSe2and GaAs. Reduction in lattice mismatch to Δa/a˜0.2% by using In0.29Ga0.71Aspseudolattice-matched substrates made possible the growth of high quality CuInSe2with predominant free exciton emissions in their photoluminescence spectra and with residual defect densities of as low as p˜l×1017cm-3implying the growth of device quality CuInSe2epitaxial films.