Intensity and wavelength dependence of the photoconductivity in Cr-doped Sr$\mathsf{_{0.61}}$Ba$\mathsf{_{0.39}}$Nb$\mathsf{_2}$O$\mathsf{_6}$

Abstract.

We examine the light-induced charge transport properties of a series of chromium-doped $\rm {Sr}_{0.61}\rm {Ba}_{0.39}\rm {Nb}_2\rm {O}_6$ single crystals by measurements of the optical absorption and the electric conductivity. By comparing the wavelength dependence of the specific photoconductivity and the optical absorption we show that both effects stem from the same center. The intensity dependence of the photoconductivity shows the applicability of a one-center charge transport model for high doping concentrations, while for low doping concentrations a more sophisticated model is needed. The validity of a one-center model is exemplarily verified for a crystal doped with 0.51 mol % Cr over a wide intensity range using a holographic method. The product of mobility and recombination time of photoexcited electrons is deduced from the specific photoconductivity.