Anomalously large measured thermoelectric power factor in Sr1-x Lax TiO3 thin films due to SrTiO3 substrate reduction

We report the observation that thermoelectric thin films of La-doped SrTiO3 grown on SrTiO3 substrates yield anomalously high values of thermopower to give extraordinary values of power factor at 300 K. Thin films of Sr0.98 La0.02 TiO3, grown via pulsed laser deposition at low temperature and low pressure (450 °C, 10-7 Torr), do not yield similarly high values when grown on other substrates. The thin-film growth induces oxygen reduction in the SrTiO3 crystals, doping the substrate n type. It is found that the backside resistance of the SrTiO3 substrates is as low (∼12) as it is on the film side after film growth. © 2008 American Institute of Physics.