Intriguing photoconductivity behaviors of SrTiO3−δ thin films with Pt contacts

The photoconductivity spectra of oxygen-deficient SrTiO3−δ thin films with Pt contacts show two intriguing peaks at and above the band gap (∼3.2 eV). The first (second) peak, located at (above) the band gap, shows hysteretic (linear) photocurrent–voltage characteristics with a long (short) relaxation time. In addition, the first (second) peak shows a weak (strong) dependence on the surface treatment of the substrate as well as the surrounding atmosphere. These results have been discussed in terms of the Schottky contact, built-in voltage, and trapping/recombination process.