Radiative recombination in CdIn 2 Se 4 : Photoluminescence spectra

l I III IV The photoluminescence of many ternary semiconductors of the A B 2 X 4 family has been studied by different authors in the last two decades (~); some interesting properties have been put in evidence, but a systematic analysis and a comparison of the results together with an interpretation of the recombination process in ternary semiconductors are still lacking. More recent works on three compounds of the family (ZnIn2S 4 (~), ZnIn~Se 4 (3) and and CdIn2S 4 (a)) seem to suggest that a unique mechanism can explain the recombinat ion process. In the light of a systematic study of all the compounds of the family, this letter deals with the luminescence of the relatively unknown cadmium indium selenide (CdIn2S%). Cadmium indium selenide is a n-type semiconductor with defect chalcopyrite structure (5); its main transport properties have been measured by KOVAL et al. (6), while BALDBR~SCHI and coworkers have calculated the energy band structure of this semiconductor; in particular, they have shown that some energy levels are very sensltive to the position of the atoms in the cell, i .e . to the internal distortion (7). The optical and photoelectrical properties have been studied in detail by TRYKOZKO (s), who has shown that the indirect and the direct gaps of CdIn~S% at liquid-nitrogen temperature are located at 1.60 eV and 1.84 eV, respectively. To the best of our knowledge there is only one published paper on the photoluminescenee of CdIn2Se a,