On optical and photoelectric properties of the LiNbO₃:Fe compounds

Abstract

For the partially reduced and oxidized LiNbO₃:Fe crystals, spectral characteristics of the optical absorption coefficient, photoconductivity and photogalvanic current have been investigated in the temperature interval 290 ÷ 473 K and energy range 2 ÷ 4 eV. Dark conductivity has been also studied in the same temperature interval. Both deep levels of Fe impurity and hole and electron polaron state were taken into account while interpreting the experimental results. Thermal activation energies of polaron mobility, as well as temperature dependence of impurity and fundamental absorption edges in the spectrum were determined. Heat-releae energy was found for band-to-band transitions and for those involving Fe level. On basis of the obtained results, a model of LiNbO₃:Fe energy spectrum is suggested, both in quasimomentum and normal coordinate spaces.