Current saturation in indium oxide based ceramics

Abstract

Current-voltage dependence for In2O3-SrO ceramics contains three regions: linear at low voltages, superlinear at intermediate voltages (current is increased stronger than voltage) and sublinear at higher voltages (current is increased weaker than voltage). The appearance of sublinear region after superlinear one cannot be explained by the existing theory. Based on the experimental data (electrical measurements, SEM and XPS) a modified grain-boundary model is suggested. In the model the additional adsorption of oxygen due to a capture of electrons at the grain-boundary states is assumed. Accordingly, the barrier height is increased and current is saturated. Calculated current-voltage dependences correspond experimentally observed ones.