Asymmetric two-site hopping model for high-electric-field-excited thermally stimulated current in evaporated silicon oxide films

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Abstract
The electrically excited thermally stimulated current (ETSC) in evaporated silicon oxide films was studied below room temperature. The experimental results had only one peak at a temperature Tm, which varied with the exciting field. The peak temperature Tm became lower and the half-width Delta T of the peak extended to the lower-temperature side as the exciting field increased. It is reasonable to adopt the two-site hopping model to analyse the ETSC results; however, it is shown that the features of the ETSC results could not be explained on the symmetric model but on the asymmetric one proposed by Pollak (1972), i.e. the depths of potential wells of the two-site pair have a difference Delta phi . The relaxation current also depended on temperature, which was distinctly observed below the temperature range where the ETSC was observed.