The influence of calcium doped ZnO films on Love wave sensor characteristics

The effects of different concentrations of Ca doped ZnO films crystalline structure on Love wave sensor characteristics were investigated in this research. Calcium doped ZnO films with c-axis preferential orientation have been grown on the ST-cut quartz substrate by RF magnetron sputtering technique. Crystalline structures and surface characteristics of films were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM); the sensitivity, electromechanical coupling coefficient, dielectric constant, and temperature coefficient of frequency of devices were measured. Sensor sensitivity increases obviously with increasing of Ca dopants but the sensitivity will be reduced when Ca over-doped.