Institute of Micro-Nanoelectronics, School of Electronics and Control Engineering, Chang'an University, Xi'an 710064, China.
Sensors (Basel). 2018 Oct 10;18(10):3384. doi: 10.3390/s18103384.
The ZnO waveguide layer for the Love wave humidity sensor was fabricated by radio frequency (RF) magnetron sputtering technique using ZnO as the target material. To investigate the effect of RF magnetron sputtering temperature on the ZnO waveguide layer and Love wave device, a series of Love wave devices with ZnO waveguide layer were fabricated at different sputtering temperatures. The crystal orientation and microstructure of ZnO waveguide was characterized and analyzed, and the response characteristics of the Love wave device were analyzed by network analyzer. Furthermore, a humidity measurement system is designed, and the performance of the Love wave humidity sensor was measured and analyzed. The research results illustrate that the performance of the ZnO waveguide layer is improved when the sputtering temperature changes from 25 °C to 150 °C. However, when the sputtering temperature increases from 150 °C to 200 °C, the performance of the ZnO waveguide layer is degraded. Compared with the other sputtering temperatures, the ZnO waveguide layer fabricated at 150 °C has the best c-axis orientation and the largest average grain size (53.36 nm). The Love wave device has the lowest insertion loss at 150 °C. In addition, when the temperature of the measurement chamber is 25 °C and the relative humidity is in the range of 10% to 80%, the fabricated Love wave humidity sensor with ZnO waveguide layer has good reproducibility and long-term stability. Moreover, the Love wave humidity sensor has high sensitivity of 6.43 kHz/RH and the largest hysteresis error of the sensor is 6%.
用于声表面波湿度传感器的 ZnO 波导层是通过射频 (RF) 磁控溅射技术使用 ZnO 作为靶材制造的。为了研究射频磁控溅射温度对 ZnO 波导层和 Love 波器件的影响，在不同的溅射温度下制造了一系列带有 ZnO 波导层的 Love 波器件。对 ZnO 波导的晶体取向和微观结构进行了表征和分析，并通过网络分析仪分析了 Love 波器件的响应特性。此外，设计了一个湿度测量系统，并测量和分析了 Love 波湿度传感器的性能。研究结果表明，当溅射温度从 25°C 变化到 150°C 时，ZnO 波导层的性能得到了提高。然而，当溅射温度从 150°C 升高到 200°C 时，ZnO 波导层的性能会下降。与其他溅射温度相比，在 150°C 下制造的 ZnO 波导层具有最佳的 c 轴取向和最大的平均晶粒尺寸（53.36nm）。Love 波器件在 150°C 时具有最低的插入损耗。此外，当测量腔室的温度为 25°C，相对湿度在 10%至 80%范围内时，用 ZnO 波导层制造的声表面波湿度传感器具有良好的重现性和长期稳定性。此外，声表面波湿度传感器具有 6.43kHz/RH 的高灵敏度，传感器的最大滞后误差为 6%。
