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-μm-thick In_0.29Ga_0.71As layer grown on a linearly composition-graded In_xGa_1-xAs buffer (0≤x≤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 CuInSe₂ films indicative of significant improvement in crystalline quality and substantial reduction in the point defect density.