The Deformation Behavior and Bending Emissions of ZnO Microwire Affected by Deformation-Induced Defects and Thermal Tunneling Effect

Abstract

The realization of electrically pumped emitters at micro and nanoscale, especially with flexibility or special shapes is still a goal for prospective fundamental research and application. Herein, zinc oxide (ZnO) microwires were produced to investigate the luminescent properties affected by stress. To exploit the initial stress, room temperature in situ elastic bending stress was applied on the microwires by squeezing between the two approaching electrodes. A novel unrecoverable deformation phenomenon was observed by applying a large enough voltage, resulting in the formation of additional defects at bent regions. The electrical characteristics of the microwire changed with the applied bending deformation due to the introduction of defects by stress. When the injection current exceeded certain values, bright emission was observed at bent regions, ZnO microwires showed illumination at the bent region priority to straight region. The bent emission can be attributed to the effect of thermal tunneling electroluminescence appeared primarily at bent regions. The physical mechanism of the observed thermoluminescence phenomena was analyzed using theoretical simulations. The realization of electrically induced deformation and the related bending emissions in single microwires shows the possibility to fabricate special-shaped light sources and offer a method to develop photoelectronic devices.

In Situ Quantification of Strain‐Induced Piezoelectric Potential of Dynamically Bending ZnO Microwires

“…The strain field and charge separation resulting from the coupling of the piezoelectric effect with semiconductor properties during M/NWs bending have been investigated using conductive atomic force microscopy (C-AFM) [14,23,26] and current-voltage characteristic measurement techniques with scanning electron microscopy (SEM). [13,27] However, their results are related to the impedance of the test loop. [28,29] Piezoresponse force microscopy (PFM) is one of the mainstream techniques in the study of the electromechanical coupling mechanism of ferroic materials.…”