Origin of the wavelength-dependence of effective trap density in photorefractive BaTiO3:Ce

Abstract

The wavelength dependence of the total effective trap density, Neff, in a photorefractive BaTiO3:Ce crystal is experimentally determined by two-beam coupling. The result shows that Neff decreases with increasing wavelength. The deep-shallow-trap model for charge transport well fits to the experimental data, indicating that the model can quantitatively explain the variation of Neff with wavelength in BaTiO3:Ce. It is concluded that the remarkable variation of the ratio of the photo ionization cross section of the deep center to that of the shallow trap with wavelength, and the higher density of the shallow traps than that of the uncompensated deep centers are significant to the variation of Neff with wavelength.