Degradation phenomena due to dc bias in low-voltage ZnO varistors

Relationship between the electrical characteristics of the low-voltage ZnO varistors and dc degradation is investigated in this study. The degradation phenomena of the low-voltage ZnO varistors due to long-time bias are studied by current–voltage (I–V) and ac measurements. After degradation, the changes observed in the properties of deep bulk trap are attributed to the alteration of defect structure.