Characterization of doped Bi4Ge3O12 single crystals by light-induced absorption, electrical and photoelectrical measurements

Abstract

Measurement of light-induced absorption changes, dark- and photoconductivity have been performed on Bi4Ge3O12 crystals doped with Fe, Rh and Fe+Rh. All samples exhibited a strong photochromic effect at room temperature, which was fully reversible after thermal annealing. It was found that Rh-doped Bi4Ge3O12 crystals possess a lower dark conductivity (sigma(d) = 5.2 x 10(-14) (Omega.cm)(-1)) at room temperature in comparison with other investigated samples. New centers in the Bi4Ge3O12 inter-band structure, with thermal activation energies between 0.25 and 0.37 eV, have been created by doping with Fe and Rh. Fe-doped and Fe+Rh co-doped samples showed a non-linear photoconductivity dependence on light intensity, under illumination with a 514-nm laser.