Growth and characterization of c-axis titled ZnO thin film by radio frequency magnetron sputtering

This work focuses on fabrication of c-axis tilted ZnO thin film which is used in FBAR biosensors to induce shear mode acoustic wave in the liquid environment. The ZnO thin film was deposited via using one-step method by radio frequency (RF) magnetron sputtering with fixed inclined angle between the normal of the target and substrates. All the samples were investigated by the SEM, XRD and UV visible spectrophotometer. It is found that the motion states of substrates and angle of tilted target decide the inclined angle of crystals growth. The sputtering pressure affects the quality of column structure. The high sputtering pressure destroy the growth of column structure. Besides, the procedure of annealing is very important for optimizing the quality and orientation of crystals growth. The thin film deposited on the static substrates at low sputtering pressure (1.0 Pa) has preferred tilted c-axis orientation column structure. The tilted angle of c-axis is 13.6 degrees and close to the value (13.1 degrees) of theory formula. As for optical transmittance of samples, the optical band gap is decreased as sputtering pressure reduces.