Title: Deep Levels Near the Grain Boundary in a Zinc Oxide Varistor: Energy Change Due to Electrical Degradation
Abstract: Localized deep levels in a ZnO varistor were investigated by isothermal capacitance transient spectroscopy, in relation to a degradation of nonlinear electrical characteristics caused by thermal treatment in a slightly reduced atmosphere. Two discrete deep levels were observed near the grain boundary. Before the degradation, they were located at 0.36 and 0.19 eV below a conduction band. After the degradation, they shifted toward the conduction band by 0.16 and 0.09 eV, respectively: the energy shift was not identical for the two levels. It was suggested that the energy shift of the localized levels reflected lattice disorders originally existing near the grain boundary or proper changes of chemical states induced by the reduction.
Publication Year: 1990
Publication Date: 1990-05-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 26
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