Gauge factors for piezotronic stress sensor in polycrystalline ZnO
Gauge factors for piezotronic stress sensor in polycrystalline ZnO
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DOI：
10.1088/1361-6463/aa65f6
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发表时间：
2017-04
期刊：
影响因子：
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通讯作者：
P. Keil;Raschid Baraki;N. Novak;J. Rödel;T. Frömling
中科院分区：
文献类型：
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作者：
P. Keil;Raschid Baraki;N. Novak;J. Rödel;T. Frömling
在过去的十年中，压电效应获得了相当大的兴趣。它利用应力诱导的压电电荷和压电半导体中的电子能带结构的相互作用。这可能导致新的应用，如应变触发晶体管或透明应变/应力传感器。除了单肖特基势垒，双肖特基势垒在ZnO压敏电阻边界可以广泛地修改的应用程序的应力。通过这种方法获得的应变计因子远远超过商业应变传感器的值。因此，确定潜在的物理机制是最重要的应变传感应用。在这项工作中，机械应力对ZnO基压敏陶瓷的电流-电压特性的影响的实验结果进行了对比模拟。它被验证，最近推出的简化的物理模型的基础上平行导电区域是能够解释压敏陶瓷的应力敏感性和应变计因子的演变作为机械应力的函数。在低于击穿电压的电场下，通过微结构的小的击穿路径决定陶瓷的电流响应。当材料在外部施加单轴压缩载荷的情况下受到机械应力时，这种电流局部化效应变得更加明显。考虑到在应力传感器中的应用，材料中的电流局部化可能导致局部加热效应和材料的退化。
The piezotronic effect gained considerable interest during the last decade. It utilizes the interaction of stress-induced piezoelectric charges and the electronic band structure in piezoelectric semiconductors. This could lead to new applications like strain-triggered transistors or transparent strain/stress sensors. Apart from single Schottky barriers, double Schottky barriers in varistor boundaries in ZnO can be modified extensively by the application of stress. The gauge factors obtained by this method far exceed values for commercial strain sensors. The determination of the underlying physical mechanisms is therefore of utmost importance for applications in strain sensing. In this work, the experimental results of the influence of mechanical stress on the current–voltage characteristics of ZnO-based varistor ceramics are contrasted to simulations. It is verified that a recently introduced simplified physical model based on parallel conductive regions is capable of explaining the stress sensitivity of varistor ceramics and the evolution of the gauge factor as a function of mechanical stress. At electric fields below the breakdown voltage, small percolating pathways through the microstructure determine the current response of the ceramic. This current localization effect becomes even more pronounced when the material is mechanically stressed with an externally applied uniaxial compressive load. Considering application in stress sensors, current localization in the material could possibly lead to local heating effects and degradation of the material.