Fowler-Nordheim tunneling and temperature effects in electrical conductivity of metal oxide varistors

The validity of Fowler-Nordheim tunneling as an electrical conduction mechanism in MOV materials was investigated in a wide temperature range. Despite the fact that, in high-field regions, the current-voltage curves conform to the relation I=B exp(−γ/V), which is formally consistent with Fowler-Nordheim tunneling, we find that the parameters B and γ are strongly temperature dependent above 60 °C. The question then arises as to whether the fit of the above relation to the I-V curves is more accidental than an indication of the Fowler-Nordheim tunneling mechanism in the whole temperature range.