Deposition and structural properties of piezoelectric ZnO epitaxial film on p-InP (1 0 0) substrate for FBAR

R.F. magnetron sputtering grown ZnO films on p-InP (1 0 0) substrates without any metallic bottom electrode were studied to investigate a possibility of this structure for FBAR application, although the substrate has a relatively high resistance. AFM images showed that the root mean square of the average surface roughness of the ZnO film was 5.88 A ° , and X-ray diffraction and transmission electron microscopy (TEM) measurements showed that the ZnO film grown on the InP were textured (or epitaxy) films with strong (0 0 0 1) preferential orientation. Auger electron spectroscopy and bright-field TEM measurements showed that the ZnO epitaxial films grown on InP at 200 8C had no any significant interdiffusion problems. These results indicate that the ZnO epitaxial films grown on p-InP (1 0 0) at low temperature hold promise for FBAR devices based on compound semiconductors substrates, such as InP and InSb, without metallic bottom electrode.