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Gauge factors for piezotronic stress sensor in polycrystalline ZnO

Keil, Peter and Baraki, Raschid and Novak, Nikola and Rödel, Jürgen and Frömling, Till (2017):
Gauge factors for piezotronic stress sensor in polycrystalline ZnO.
In: Journal of Physics D: Applied Physics, IOP Publishing, p. 175106, 50, (17), ISSN 0022-3727, [Online-Edition: https://doi.org/10.1088/1361-6463/aa65f6],
[Article]

Abstract

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.

Item Type: Article
Erschienen: 2017
Creators: Keil, Peter and Baraki, Raschid and Novak, Nikola and Rödel, Jürgen and Frömling, Till
Title: Gauge factors for piezotronic stress sensor in polycrystalline ZnO
Language: English
Abstract:

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.

Journal or Publication Title: Journal of Physics D: Applied Physics
Volume: 50
Number: 17
Publisher: IOP Publishing
Uncontrolled Keywords: piezotronics, stress sensitivity, ZnO-based varistor
Divisions: 11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences
Date Deposited: 11 Apr 2017 12:28
Official URL: https://doi.org/10.1088/1361-6463/aa65f6
Identification Number: doi:10.1088/1361-6463/aa65f6
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