ELECTRICAL-PROPERTIES OF AU/NB-DOPED-SRTIO3 CONTACT

Current-voltage measurements for Au/Nb-doped-SrTiO3 contacts have been performed over a temperature range from 4.2 to 277 K. The forward characteristics above 46 K are well described by the Schottky diode model. The temperature dependence of the parameter E{ = [partial-log I/partial(qV)]-1} and the saturation current I(S) show that a thermionic-field emission is dominant in the carrier transport mechanism across contacts above 101 K. It is found that the parameter E is too large compared with an estimated value from the Schottky diode model using a permittivity obtained from the inverse characteristics of capacitance-voltage measurements. We discuss the barrier properties and suggest the possibility of imperfect ionization of the impurity Nb at the surface of the SrTiO3:Nb substrate.