Pulsed Laser Deposition and Acoustic Property of Piezoelectric / Nonpiezoelectric Multilayer Films

Abstract

Piezoelectric/nonpiezoelectric multilayer films were prepared by using pulsed laser deposition technique. The piezoelectric ZnO layers were completely (0001) textured and had the piezoelectric coefficient d₃₃. The nonpiezoelectric (inactive) Al₂O₃ layers were amorphous and acted as good media for microwave and supersonic wave propagation. The periods were controlled by the deposition time in the range of 2.0 to 400 nm with the total period number of 4 to 30. In the multilayer films with ultrashort period of 2.1 nm, (0002) X-ray diffraction peak of ZnO layers was considerably broadened by the noncrystalline Al₂O₃ layers. In the multilayer films with short period of 6.4 nm, the diffraction peaks presented in small angle implies that the interfaces between layers were much flat and sharp, And in the multilayer films with long period, (0002) peak was very sharp, similar to the normal ZnO thin films. High frequency resonance was measured in the long-period multilayer films in the range of 1 - 20 GHz and higher frequency resonance is expected in the multilayer films with shorter period.