Study of Trapping Phenomena in SrTiO\u3csub\u3e3\u3c/sub\u3e by Thermally Stimulated Techniques

Thermally stimulated current (TSC), thermally stimulated depolarization current (TSDC), and thermally stimulated luminescence (TSL) spectroscopies were combined to study trapping phenomena in undoped bulk SrTiO3 crystals. Electrical measurements were also performed and showed that the crystals are highly resistive in the dark but exhibited an unusually high photocurrent upon 400-nm illumination. Several traps were revealed in both TSC and TSDC spectra between 83 K and 450 K in such a broad temperature range and their activation energies were extrapolated from the trap positions (peaks). TSL spectra demonstrate similar characteristics comparable to TSC and TSDC spectra, though there are some differences because of different excitation and recombination mechanisms. This work reveals the presence of large number of traps in SrTiO3 single crystals, which are most likely the source of many of the interesting phenomena in SrTiO3 such as transient and persistent photoconductivity