Pulsed laser deposition-induced reduction of SrTiO3 crystals

We report a generic method for fast and efficient reduction of strontium titanate (SrTiO3, STO) single crystals by pulsed laser deposition (PLD) of thin-films. The reduction was largely independent of the thin-film material deposited on the crystals. It is shown that thermodynamic conditions (450 °C, 10−7 torr, 10–60 min), which normally reduce STO (0 0 1) substrates to roughly 5 nm into a crystal substrate, can reduce the same crystals throughout their 500 μm thickness when coupled with the PLD. In situ characterization of the STO substrate resistance during thin-film growth is presented. This process opens up the possibility of employing STO substrates as a back-gate in functional oxide devices.