High-quality epitaxial films were grown by molecular beam epitaxy. The films exhibited largely free exciton emissions in photoluminescence spectra, and were grown by optimizing the growth conditions. Native defects were then systematically investigated. A common acceptor-type defect was identified to be VCu. Unlike films which were grown under Cu-excess conditions, films which were grown under an In excess tended to be heavily compensated, and the origin of the donor-type defects in these films was found to be Cu¯Se divacancies, VCu-Se. Annealing in air, the presence of a Cu¯Se second phase and Na interdiffusion from a soda-lime glass substrate were found to suppress VSe formation.

Molecular Beam Epitaxial Growth and Characterization of CuInSe2 and CuGaSe2 for Device Applications. S.Niki, A.Yamada, R.Hunger, P.J.Fons, K.Iwata, K.Matsubara, A.Nishio, H.Nakanishi: Journal of Crystal Growth, 2002, 237-239, 1993-9