Studies Of Preparation And Properties Of AlN Piezoelectric Film And AlN/FeNi Heterostructures

As a Ⅲ-Ⅴ compounds, aluminum nitride (AIN) thin films have been widely studied and applied in magnetic recording, the sensing technology and high frequency acoustic resonator micro-electromechanical system (MEMS) because of its good piezoelectric, thermal stability and high electromechanical coupling coefficient. The AIN piezoelectric thin film is sensitive to preparation parameters. However the preparation of the high quality of AIN piezoelectric thin film does not have standard parameters. We try to use the reactive magnetron sputtering, which has the advantages of magnetron sputtering and reactive sputtering, to realize the fast growth of high quality AIN piezoelectric thin film at room temperature. Using the converse magnetoelectric coupling effect, high quality AIN piezoelectric thin film can produce deformation to regulate the orientation of the magnetic moment of magnetic layer and to realize the information recording and storage with low power consumption and nonvolatile characters under the effect of voltage. In this paper, the preparation of the high quality of C axis preferred orientation AIN, the interface properties of AIN/FeNi and the electric control of the orientation of the magnetic moment in AIN/FeNi heterostructures were investigated. The main results are as follows:C axis orientation AIN films were prepared on corning glass substrate in the high vacuum environment using reactive magnetron sputtering technique, then the spin wave resonance technique was used to study the interface features of the piezoelectric/ferromagnetic AIN/FeNi and FeNi/AIN heterostructures. In addition to the uniform ferromagnetic resonance (FMR) absorption peak on the resonance spectrum, surface spin wave resonances were observed with magnetic field (H) in the film plane. At low temperature we identified a high-order standing spin wave in our samples and found a "critical angle" where only a uniform ferromagnetic resonance was observed as H rotating away from the film normal direction and larger than this critical angle. Based on the analysis of the angular dependence of resonance field, an in-plane biaxial anisotropy was observed and confirmed by the angular dependence of remanence ratio measurement at room temperature.As a result of the four fold magnetic symmetry of AIN/FeNi heterostructure, the electric field can induce the deformation of AIN piezoelectric layer to regulate the magnetic moment orientation, which can be used to store information. Using the measurement systems of magneto-optic Kerr effect and the magneto-resistance effect, the studies of voltage regulation of magnetic properties in AIN/FeNi heterostructures were proceeded. The results shows that the generated strain of AIN piezoelectric thin film was clamped by the substrate.