Photoluminescence spectra of some ternary and quaternary chalcopyrite semiconductors

Photoluminescence (PL) emission spectra of single crystals and thin films of CuGaxIn1−xSe2 compounds have been investigated at various measuring temperatures, and compared with the emission from CuGaSe2 and CuInSe2. The observed PL spectra consisted of two groups of emission lines: the near-band-gap group (A) and the lower energy group (B). It was found that the type of emission obtained is determined by the amount of stoichiometry and molecularity deviations. The PL data also showed a correspondence between the defect related transitions from the CuGaxIn1−xSe2 solid solution and CuGaSe2 for x<0.5. Based on the intrinsic defect states in the two components CuInSe2 and CuGaSe2, the predominant defect states transitions in the solid solution are defined for the m<1 and ΔS>0. Interpretation of the PL spectra of Se-deficient compounds with m>1 are rather complicated, and much work remains to be done before the defect chemistry of CuGaxIn1−xSe2 could be fully understood.