High quality CuInSe2 films grown on pseudo-lattice-matched substrates by molecular beam epitaxy

CuInSe2 films have been grown by molecular beam epitaxy on pseudo-lattice-matched substrates that consist of a 1-mu m-thick In0.29Ga0.71As layer grown on a linearly composition-graded InxGa1-xAs buffer (0 less than or equal to x less than or equal to 0.29) grown in turn on GaAs (001). The properties of these films have been compared with those of the films grown directly on GaAs (001). High resolution x-ray diffraction analysis on CuInSe2 grown on pseudo-lattice-matched substrates indicated substantial reduction on residual strain in the CuInSe2 films. A photoluminescence spectrum dominated by sharp free exciton emissions has been observed for the first time from CuInS2 films indicative of significant improvement in crystalline quality and substantial reduction in the point defect density. (C) 1996 American Institute of Physics.