ABSTRACT
The REBIC technique has been successfully utilised for the characterisation of ZnO varistor devices. Qualitative REBIC images, quantitative REBIC line scans and conventional IV characteristics have been obtained for a range of specimens of differing quality and condition. The images and line scan data clearly show the occurrence of contrast terraces, the number and extent of which appear to correlate well with the IV plots and hence the quality of the varistor material. Poor quality or deliberately damaged varistors gave images with multiple terrace contrast, linear line scans and linear IV characteristics whereas undamaged specimens showed marked non-linearity in the quantitative responses and a single bright-dark contrast in the REBIC image. It is thought, therefore, that the presence and form of the terraces could be used to provide, at the very least, a qualitative measure of the quality of the varistor material.
