Surface Acoustic Wave Humidity Sensors Based on (1120) ZnO Piezoelectric Films Sputtered on R-Sapphire Substrates
WANG Yan1,2**, ZHANG Shu-Yi1**, FAN Li1, SHUI Xiu-Ji 1, YANG Yue-Tao1
1Lab of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 2School of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046
Abstract：ZnO films on R-sapphire substrates are prepared and characterized by x-ray diffraction and scanning electron microscopy, which indicate that the thin films are well crystallized with (1120) texture. Love wave and Rayleigh wave are used for fabrications of humidity sensors, which are excited in [1100] and [0001] directions of the (1120) ZnO piezoelectric films, respectively. The experimental results show that both kinds of sensors have good humidity response and repeatability, and the performances of the Love wave sensors are better than those of the Rayleigh wave sensors at room temperature. Moreover, the theoretical calculations of the mass sensitivity of the sensors are also carried out and the calculated results are in good agreement with the experimental measurements.
2015, Vol. 32 
