Time-resolved measurements of photoconductivity in cerium-doped photorefractive strontium－barium niobate using nanosecond light pulses

摘要

Time-resolved measurements of photoconductivity in photorefractive strontium-barium niobate crystals doped with cerium are performed. The crystals are illuminated with nanosecond light pulses of a Q-switched frequency-doubled Nd:YAG laser 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 yields the lifetime of electrons in the conduction band. The carrier lifetime decreases and the photoconductivity increases with increasing cerium concentration in the crystals. The observed dependences and previous measurements of integrated conductivity are explained considering the participation of shallow levels in the charge transport.