The Study of the Electrical Properties of a Single Grain Boundary in Metal Oxide Varistors

Small signal AC and DC responses of a single grain boundary in commercial low voltage Metal Oxide Varistor materials were examined. Two electron traps at the depth 0.16 eV and 0.33 eV below the conduction band edge were characterized using Lump Parameter/Complex Plane Analysis. The origin of these traps was attributed to native defects in ZnO, ionized zinc interstitial, Zn, and ionized oxygen vacancy, VO, respectively. This study tends to suggest that the origin of depression angle, commonly observed in AC Impedance Spectroscopy, could result from non-ideal relaxation for the intrinsic defects within a single boundary. The I-V and Mott-Schottky responses of a single grain boundary in the present study were found to be in an excellent agreement with previous multi-junction studies