Local electronic transport at grain boundaries in Nb-doped SrTiO3 -: art. no. 235304

The local electrostatic properties and electronic transport at Sigma5 grain boundaries in donor-doped SrTiO3 bicrystals are examined using a combination of scanning probe microscopy (SPM) techniques and impedance spectroscopy. A combination of scanning surface potential microscopy (SSPM) and scanning impedance microscopy is used to determine intrinsic current-voltage and capacitance-voltage characteristics of the interface, eliminating the bulk and contact contributions. Conductive atomic force microscopy is used to directly image the depletion barrier associated with the grain boundary. The sign of the grain boundary potential is unambiguously determined by SSPM once the mobile charge effect is taken into account. A combination of SPM and impedance spectroscopy allowed the effect of grain boundary on local static and frequency dependent transport properties to be established.