Radiative recombination in CuGaS2 thin films, deposited by metalorganic vapour phase epitaxy, was studied by photoluminescence spectroscopy. From photoluminescence studies of several series of layers grown under various growth conditions, a clear picture emerges of the radiative emission dominating for Cu-rich and Ga-rich layers. For near-stoichiometric layers, weak excitonic recombination at about 2.48eV and a donor–acceptor line at about 2.4eV were observed in the low temperature photoluminescence spectra. In Cu-rich layers, a donor–acceptor band at about 2.18eV dominates, while a band at about 2.25eV dominates for slightly Ga-rich material. For Ga-rich layers, deviations from the ideal Cu/Ga ratio of more than a few percent strongly quenches the emission above 2eV in favour of a very broad band at about 1.8eV. The photoluminescence response was discussed within the context of fluctuating potentials in compensated material and compared to available reports in literature.

Defect Chemistry in CuGaS2 Thin Films - a Photoluminescence Study. J.R.Botha, M.S.Branch, P.R.Berndt, A.W.R.Leitch, J.Weber: Thin Solid Films, 2007, 515[15], 6246-51