Photoluminescence of CdIn 2 S 4 and Mixed Crystals with In 2 S 3 as Related to Their Structural Properties

In this paper experiments on photoluminescence (emission and excitation spectra) of CdIn 2 S 4 crystals and of mixed crystals with In 2 S 3 at 77°K are reported. The results are interpreted on the basis of the partial inversion of the thiospinel CdIn 2 S 4 . In CdIn 2 S 4 the two emission bands observed in the red spectral region are ascribed to a Cd ion at an octahedral site and an In ion at a tetrahedral site. This model describes the intensity and wavelength variation of the photoluminescence of the mixed crystal system CdIn 2 S 4 /In 2 S 3 surprisingly well. Evidence is given that the energy gap in all these crystals is indirect. In an appendix some etching procedures are listed.