Unusual ultraviolet photoconductivity in single crystalline SrTiO3

In this paper, ultraviolet photoconductivity of single crystalline SrTiO3 is studied. It is found that the photoconductivity of SrTiO3 arises from intrinsic band-to-band excitation, and photoconductivity increases monotonously with decreasing temperature and undergoes six or seven orders of magnitude enhancement from room temperature to 10 K. In particular, at and below 105 K, the structural transition temperature, SrTiO3 is highly ultraviolet-sensitive, and the photoconductivity increases drastically so that a TCR (temperature coefficient of resistance) similar to 30% is observed. Moreover, it is the first time that an anomaly is observed in photoconductivity at around 65 K and 37 K respectively. These results will shed light on our understanding of the band structure of tetragonal-phase SrTiO3, and the physics of SrTiO3 at lower temperatures.