High temperature transport properties at metal/SrTiO3 interfaces

High temperature current-voltage characteristics were investigated with a N b doped SrTiO3 (NbSTO) single crystal. The conductivity of the 0.5 wt% Nb d oped SrTiO3 showed high n-type conductivity with a negative temperature coe fficient. The Pt/Nb-STO interface freshly, prepared by laser ablation at 97 3 K in high vacuum condition showed ohmic behavior. However, it turned to s how a Schottky type non linearity when annealed in oxygen gas at temperatur es higher than 773 K The I-V curve in the forward direction was well,fitted with the equation based on the thermionic emission model. At high temperat ures, the I-V behavior was dependent on the oxygen partial pressure. The lo wer oxygen partial pressure resulted in a lower barrier height. The change in the I-V curve with oxygen potential was almost reversible at 873 K, and was frozen below 673 K. Those phenomena suggested that the Schottky barrier formation at the Pt/STO interface has a strong relation with the oxygen tr ansport in Nb-STO. (C) 1999 Elsevier Science Limited. All rights reserved.