Copper indium diselenide (CuInSe2, CIS) layers were grown on GaAs(100) substrates using a hot wall epitaxy (HWE) method. The optimum temperatures of the substrate and the source for the growth turned out to be 410 and 620 oC, respectively. The CIS layers were epitaxially grown along the <112> direction and kept the initial mole fraction during the layer growth. Based on an absorption measurement, the band-gap variation of CIS was well interpreted by Varshni's equation. However, the energy difference, 180 meV, of the band gap between liquid helium and room temperatures was a very large value, unlike that reported for CIS. Also, from the low-temperature photoluminescence measurement, the acceptor impurities in the CIS layers were confirmed to be native defects of VCu and/or Seint, which were deeply located at 73.8 meV above the edge of the valence band.

Keywords: CuInSe2 film, optimum growth condition, band gap energy, acceptor impurity, photoluminescience