TIME-RESOLVED MEASUREMENTS OF PHOTOCONDUCTIVITY IN CERIUM-DOPED PHOTOREFRACTIVE STRONTIUM-BARIUM NIOBATE USING NANOSECOND LIGHT-PULSES

Time-resolved measurements of photoconductivity in photorefractive str ontium-barium niobate crystals doped with cerium are performed, The cr ystals are illuminated with nanosecond light pulses of a Q-switched fr equency-doubled Nd:YAG lasts and an external electric field is applied to the samples. Light-induced drift current is amplified and detected with a fast oscilloscope. The relaxation time of photoconductivity yi elds the lifetime of electrons in the conduction band. The carrier lif etime decreases and the photoconductivity increases with increasing ce rium concentration in the crystals. The observed dependences and previ ous measurements of integrated conductivity are explained considering the participation of shallow levels in the charge transport. (C) 1998 Elsevier Science B.V.