MOLECULAR-BEAM EPITAXIAL-GROWTH AND PROPERTIES OF CUINSE2

CuInSe2 (CIS) films with Cu/In ratios (gamma) ranging from 0.81 to 1.8 1 have been grown by molecular beam epitaxy on (001)-oriented GaAs sub strates at a substrate temperature of T(s) = 450-degrees-C. It is foun d that Cu-rich films tend to become Se-poor, and In-rich films tend to become Se-rich. X-ray diffraction patterns obtained from these films have shown the peaks with respect to CIS {n00} planes, clearly indicat ing epitaxial growth. Optical properties of the CIS films have been ch aracterized by means of photoluminescence (PL) spectroscopy at 2 K. Ma ny distinct emission lines including a band edge emission were present on PL spectra obtained from Cu-rich films. A broad emission (lambda a pproximately 1.45 mum) appeared at gamma = 1.04, then became dominant with further decreasing gamma.