We report an electrical breakdown (EBD) at metal/ZnO junctions in varistors with Ag-Pd and Pd electrodes. It was found that these junctions show Schottky behaviour with a mean Schottky barrier height (SBH) of 0.70 ± 0.07 eV for Bi-based varistors with Ag-Pd (80−20 %) electrodes and a mean SBH of 0.47 ± 0.03 eV for Pr-based varistors with Pd electrodes. All investigated electrode-to-grain junctions (EGJ) exhibited an EBD of the Schottky barrier in the reverse current direction, whereas the mean EBD voltage for the Bi-based varistors is 3.5 V and 2.5 V for the Pr-based varistors. Observation of electroluminescent light at the EGJ interface clearly indicates that the EBD is related to electron-hole generation, similar to the EBD at the grain boundaries in the ZnO microstructure. This shows that a similar good but asymmetric varistor effect, as it is observed at grain boundaries, can be observed at EGJ.

我们报告了带有Ag-Pd和Pd电极的压敏电阻中金属/ ZnO结的电击穿（EBD）。发现这些结显示出肖特基行为，带有Ag-Pd（80-20％）电极的Bi基压敏电阻的平均肖特基势垒高度（SBH）为0.70±0.07 eV，Pr的平均SBH为0.47±0.03 eV Pd电极的压敏电阻。所有研究的电极-晶粒结（EGJ）都在反向电流方向上表现出肖特基势垒的EBD，而Bi基压敏电阻的平均EBD电压对于Pr基压敏电阻为3.5 V和2.5V。在EGJ界面上观察到电致发光的光清楚地表明，EBD与电子空穴的产生有关，类似于ZnO微结构中晶界处的EBD。这表明类似的良好但不对称的压敏电阻效应，