Prebreakdown Conduction in Zinc Oxide Varistors: Thermionic or Tunnel Currents and One-step or Two-step Conduction Processes

M.S. CASTRO; C.M. ALDAO

APPLIED PHYSICS LETTERS

AMER INST PHYSICS

Lugar: New York; Año: 1993 vol. 63 p. 1077 - 1079

0003-6951

This letter is aimed at understanding the intergranular conduction in zinc oxide varistors. In particular, we have studied current-voltage and Arrhenius plots of the resistive current for the prebreakdown conduction. A current-temperature (I-T) relation has been found to present two breaks at -370 and -240 K. Although this result can be interpreted as a consequence of distinct regimes, we found that experimental I-T curves can be theoretically reproduced by calculating currents for a double Schottky barrier. Experimental results were fitted with oneand two-step transport process models. It was found that a two-step model better reproduces the electrical properties of these devices.