Preparation and Optical Properties of ZnIn₂Se₄ Crystals

Absorption edge, photoresponse, and reflectance measurements have been carried out on ZnIn2Se4 crystals grown by means of chemical transport reactions. Indirect and direct energy gaps were determined as E gi=1.74 eV and E gd=1.92 eV at LNT. Reflectance measurements have been done in the 1.5–25 eV energy range. The Kramers-Kronig analysis has been performed and optical constants of studied semiconductor have been claculated. Reflectance data (R) and calculated imaginary part (ε 2) of dielectric function allowed to make some conclusions about interband transitions. Singularities in R, ε 2 and valence electron concentration per atom (neff) were basis for conclusion that d band–conduction band transitions at energy about 12.5 eV have been observed. </jats:p

Photoluminescence Study of CuIn_1-xGa_xSe₂ Mixed Crystals

Photoluminescence of CuIn1-x Ga x Se2 mixed crystals has been investigated. The emission band maximum shifts towards higher photon energies with increasing excitation intensity indicating the donor-acceptor recombination mechanism. The energies of the shallow defect states have been determined from the thermal quenching curves. </jats:p