Direct Observation of Asymmetry in the Barrier Structure of Zinc Oxide Varistors Using REBIC microscopy.

摘要

SEM-based remote electron beam induced current (REBIC) microscopy has been used to investigate the electrical characteristics of individual grain boundaries in a sintered varistor, prepared from zinc oxide doped with bismuth and antimony oxides. Resistive and EBIC contrast was observed. Partial suppression of the EBIC contrast at many grain boundaries was found to be controlled by the orientations of the grain boundary planes on either side of the interface. Variations in EBIC contrast were observed along the length of a single grain boundary and related To local changes in the barrier characteristics. The peak EBIC signal was measured as a function of Beam current and found to approach a saturation value due to the effects o screening.