Study on preparations and characterizations of ZnO nano-structural films and related SAW sensors

ZnO nano-structural films are prepared by RF magnetron sputtering and hydrothermal synthesis. The crystal structures, morphologies and chemical compositions of the ZnO nano-scaled films are analyzed by XRD, SEM and XPS. The results show that the ZnO nanorods are well oriented along c-axis as the preparing conditions are suitably selected. Meanwhile, there are a lot of oxygen vacancies and adsorbed oxygen atoms in the ZnO nano-structural films, which are beneficial to be utilized as gas-sensing materials. Furthermore, SAW (Rayleigh wave and Love wave) sensors based on ZnO nanorod films deposited on 128° YX-LiNbO₃ and 36° YX-LiTaO₃ piezoelectric substrates are fabricated and used for hydrogen sensing at room temperature. The results indicate that the Love wave sensors have superior sensing properties, such as high sensitivities.