Semiconducting properties of ZnOndash;grainhyphen;boundaryndash;ZnO junctions in ceramic varistors

摘要

The capacitancehyphen;voltage (Chyphen;V) curves and their frequency dependence are measured for ZnO varistors. Within the band picture of ZnOndash;grainhyphen;boundaryndash;ZnO junctions, the prebreakdown portion of theChyphen;Vcurves is calculated selfhyphen;consistently to 1percnt;. The strong frequency dependence of the capacitance at higher bias is shown to be consistent with the formation of an inversion layer near the grain boundary.