CuGaSe2 (CGS) layers were grown by the hot wall epitaxy method. The optimum temperatures of the substrate and source for the growth turned out to be 450 and 610 oC, respectively. The CGS layers were epitaxially grown along the <110> direction and retained the initial mole fraction during the layer growth. Based on an absorption measurement, the band-gap variation of CGS was well interpreted by Varshni's equation. But, the band-gap energies at low temperatures were large values unlike that of other CGS. From a low-temperature photoluminescence experiment, sharp and intensive free- and bound-exciton peaks were observed. By analyzing these emissions, a band diagram of the observed optical transitions was obtained.

Keywords: A1. Characterization, A3. Hot wall epitaxy, B2. Semiconducting ternary compounds.