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为了从微观角度解释ZnO压敏电阻的导电机理,利用电声脉冲(PEA)法,对4种ZnO压敏电阻试样在不同电流密度下的空间电荷分布特性进行了试验.研究结果表明,空间电荷和电流密度之间的关系与伏安特性曲线具有一致性,可以反映非线性特性.在小电流区,空间电荷与场强和电流密度呈线性关系,空间电荷的增加反映了晶界层表面态的减少和肖特基势垒的变化.小电流区到中电流区存在过渡区,过渡区的电流是由热电子激活和隧道电流共同构成.在中电流区,随着电流的增大,空间电荷会呈减小趋势,当耗尽层减小为零时,空间电荷会基本消失.
In order to explain the conduction mechanism of ZnO varistor from the microscopic point of view, the space charge distribution characteristics of four kinds of ZnO varistor samples at different current densities were tested by electro-acoustic pulse (PEA) method.The results show that space The relationship between the charge and the current density is consistent with the volt-ampere characteristic curve and reflects the nonlinear characteristic. In the small current region, the space charge has a linear relationship with the field strength and the current density, and the increase of the space charge reflects the surface of the grain boundary layer State reduction and Schottky barrier change.Low current area to the middle current area there is a transition zone, the transition zone current is composed of hot electron activation and tunnel current together in the current region, with the current increases, The space charge will decrease. When the depletion layer is reduced to zero, the space charge will disappear.