Influence of defect segregation on the electrical properties of nb-doped SrTiO3 grain boundary layer

Abstract

The influences of defect segregation on electrical properties were investigated for a single grain boundary layer in Nb-doped SrTiO3. The electrical properties were compared with those of a grain embedded with a platinum wire. On the basis of the current-voltage (I-V) characteristics, it was found that the grain boundary of Nb-doped SrTiO3 could be presented as a back-to-back double Schottky model. The segregation of defects, strontium vacancies, in grain boundary was suggested from the results of current-time (I-t) measurement, impedance spectroscopy, and capacitance-voltage (C-V) measurement. It was also postulated that the space charge originating from this defect segregation forms the potential barrier. The activation energy for conduction through a grain boundary changed with applied voltage from 1.60 eV to 0.97 eV.