Surface Morphology and Liquid Sensor Sensitivity of Barium-Doped ZnO Thin Film

Barium-doped ZnO films were deposited on ST-cut quartz by radio frequency magnetron sputtering. The crystal structure and surface morphology of barium-doped ZnO films were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. ZnO film with a large grain size, rough surface, and porous structure was obtained by adding barium. The sensitivity of the liquid sensor with 2.0 mol% barium-doped ZnO films reached -32.5410-8m2skg-1, which was over 3 times higher than that of pure ZnO film. The temperature coefficient of frequency decreased from +5.80ppm/°C for pure ZnO film to +1.21ppm/°C for 3.0mol% barium-doped ZnO film. The sensitivity and temperature coefficient of frequency of the Love wave liquid sensor improved greatly for ZnO film doped with the optimum barium concentration.