Kim Junyoung, Lee Eunho, Mehta Gayatri, Choi Wonbong
Department of Materials Science and Engineering, University of North Texas, Denton, TX 76207, United States of America.
Department of Mechanical and Energy Engineering, University of North Texas, Denton, TX 76207, United States of America.
Nanotechnology. 2020 Oct 30;31(44):445203. doi: 10.1088/1361-6528/aba659. Epub 2020 Jul 15.
Piezoelectric materials are widely used as electromechanical couples for a variety of sensors and actuators in nanoscale electronic devices. The majority of piezoelectric devices display lateral patterning of counter electrodes beside active materials such as two-dimensional transition metal dichalcogenides (2D TMDs). As a result, their piezoelectric output response is strongly dependent on the lattice orientation of the 2D TMD crystal structure, limiting their piezoelectric properties. To overcome this issue, we fabricated a vertical sandwich design of a piezoelectric sensor with a conformal contact to enhance the overall piezoelectric performance. In addition, we enhanced the piezoelectric properties of 2D WS by carrying out a unique solvent-vapor annealing process to produce a sulfur-deficient WS structure that yielded a 3-fold higher piezoelectric response voltage (96.74 mV) than did pristine WS to a 3 kPa compression. Our device was also found to be stable: it retained its piezoelectric performance even after a month in an ambient atmospheric condition. Our study has revealed a facile methodology for fabricating large-scale piezoelectric devices using an asymmetrically engineered 2D WS structure.
压电材料作为机电耦合器，在纳米级电子设备中的各种传感器和致动器中得到了广泛应用。大多数压电器件在诸如二维过渡金属二硫属化物（2D TMDs）等活性材料旁边显示出对电极的横向图案化。因此，它们的压电输出响应强烈依赖于2D TMD晶体结构的晶格取向，限制了它们的压电性能。为了克服这个问题，我们制造了一种垂直夹层设计的压电传感器，具有共形接触，以提高整体压电性能。此外，我们通过进行独特的溶剂-蒸汽退火工艺来增强二维WS的压电性能，以产生硫缺陷的WS结构，该结构对3 kPa压缩产生的压电响应电压（96.74 mV）比原始WS高出3倍。我们还发现我们的器件很稳定：即使在环境大气条件下放置一个月后，它仍能保持其压电性能。我们的研究揭示了一种使用不对称工程二维WS结构制造大规模压电器件的简便方法。
