Properties of Deep Levels in ZnO Varistors and Their Effect on Current-Response Characteristics

Abstract

Deep level transient spectroscopy is successfully applied to detect and characterize trap centers in ZnO varistors. Three electron traps with activation energies of 0.18, 0.30 and 0.36 eV are detected. The measured time constants of these traps are shown to be correlated with the observed transient current responses, indicating the necessity of removing these slowlyresponding trap levels to realize very fast ZnO varistors.