Time dependence of the electrical conductivity in strontium titanate single crystals

Measurements of the apparent electrical conductivity of high resistivity single crystal slices of SrTiO 3 are reported. It is shown that the behaviour is strongly dependent on the electrode material employed. In particular gold and silver anodes lead to a substantial increase of current with time followed by a plateau. It is suggested that the effects observed could be accounted for by the formation of an anodic layer at the anode-crystal interface leading to enhanced hole injection. Etching experiments are described which lead to distinct results depending on whether the crystals were grown by the flame fusion method or the fluxed melt method. These results are discussed in relation to the electrical measurements.