ZnO压敏陶瓷势垒高度的测量及其应用

The Measurement and Application of Schottky Barrier Height of ZnO Varistor Ceramics

系统分析了势垒高度测量的两种常用方法(I-T特性方法和C-V特性方法)成立的条件,发现直接采用lnj～1/T曲线的基本I-T特性方法适用于流过ZnO压敏陶瓷的电流较小,导电机制为热发射电流的情况,且只能得到等效势垒高度,其最大误差为12%～20%。要使测量误差在10%以内,则外施电压的荷电率不应超过0.4～0.6。改进后的I-T特性方法可测量零偏置电压下的势垒高度准0;C-V特性方法仅适用于偏析层厚度可忽略的情况,否则测量值明显偏大;实际上将两种方法相结合,不但能得到较精确的势垒高度准0,还能获得偏析层的厚度。

The condition of two methods（I-T property method and C-V property method） for measurement of Schottky barrier height are analyzed systematically.It is found that basic I-T property method with lnj～1/T curve is applicable to the condition that the current flow over the ZnO varistor ceramic is smaller,and its mechanism for conducting is thermal emission current and only equivalent barrier height can be obtained and the maximum error is about 12%～20%.the chargeability of applied voltage should no more than 0.4～0.6 to make measurement error decrease to lower 10%.The true barrier height ф 0 can be obtained by I-T property method.C-V property method only applicable to thick of grainboundary layer,otherwise the measurements will be obvious bigger In fact,the two methods can be used at the same time and not only the true barrier height ф 0 but also the thickness of segregated layer can be obtained.