Optical and Structural Properties of n-CuIn3Se5 Single Crystals

Structural characterization of sample was carried out through the Laue showing a very perfect ternary symmetry and a high crystallinity. Optical absorption was investigated in CuIn3Se5 in the temperature range 85-300K. The energy gap (1.42 eV at 85K) and its temperature dependence were determined. The latter was studied by means of a three-parameter thermodynamic model and the Einstein model. The values of the band gap at zero temperature, average phonon energy, and a dimentionless constant related to the electron-phonon coupling were estimated. Band tail states were found to give rise to the absorption below the fundamental edge.