绝缘介质中载流子注入与传导的机理

Injection and Conduction Mechanisms of Charge Carriers in Insulators

本文分析了与绝缘介质老化、失效过程密切相关的载流子注入与传导机理,包括具有电极限制特性的肖特基效应、具有体限制特性的普尔-弗兰凯尔效应、隧穿效应、离子跳跃传导以及空间电荷限制电流。研究结果表明:由普尔-弗兰凯尔效应引起的势垒降低的高度是由肖特基效应降低的势垒高度的两倍。如果In(I/E2)-1/E特性关系始终是线性的,说明载流子是由隧穿效应注入介质中的。在高电场下,离子跳跃传导的J-E特性曲线是一条斜率为eλ/2kT的直线,并可由此斜率计算得到离子跳跃的距离。由空间电荷限制电流的J-V特性可以确定临界电压,即电流从陷阱限制值迅速跳高至无陷阱的空间电荷限制电流值的电压。

Injection and conduction of charge carriers are closely related with the aging and failure process of insulating materials.Their mechanisms were analyzed in this paper,including Schottky effect characterized by electrode-limited conducting process,Poole-Frenkel effect characterized by bulk-limited conducting process,tunneling effect,ionic hopping conduction and space charge limited current.Results reveal that the reduction of barrier height caused by Poole-Frenkel effect is two times of that caused by Schottky effect.If In（I/E^2）-1/E characteristic is always linear,it indicates that charge carriers are injected into the dielectric medium through tunneling effect.Under the high electric field,J—E characteristic of ionic hopping conduction is a straight line with the slope eλ/2kT,from which ionic hopping distance can be calculated.Critical voltage can be obtained through J—V characteristics of space charge limited current,namely the voltage at which current rapidly jumps from trap limited to space charge limited current without traps.