Emanetoglu N W, Patounakis G, Liang S, Gorla C R, Wittstruck R, Lu Y
Department of Electrical and Computer Engineering, Rutgers University, Piscataway, NJ 08854-8058, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2001 Sep;48(5):1389-94. doi: 10.1109/58.949748.
ZnO thin films with a high piezoelectric coupling coefficient are widely used for high frequency and low loss surface acoustic wave (SAW) devices when the film is deposited on top of a high acoustic velocity substrate, such as diamond or sapphire. The performance of these devices is critically dependent on the quality of the ZnO films as well as of the interface between ZnO and the substrate. In this paper, we report the studies on piezoelectric properties of epitaxial (1120) ZnO thin films grown on R-plane sapphire substrates using metal organic chemical vapor deposition (MOCVD) technique. The c-axis of the ZnO film is in-plane. The ZnO/R-Al2O3 interface is atomically sharp. SAW delay lines, aligned parallel to the c-axis, were used to characterize the surface wave velocity, coupling coefficient, and temperature coefficient of frequency as functions of film thickness to wavelength ratio (h/lambda). The acoustic wave properties of the material system were calculated using Adler's matrix method, and the devices were simulated using the quasi-static approximation based on Green's function analysis.
当在诸如金刚石或蓝宝石等高声速衬底上沉积薄膜时，具有高压电耦合系数的氧化锌（ZnO）薄膜被广泛用于高频和低损耗表面声波（SAW）器件。这些器件的性能严重依赖于ZnO薄膜以及ZnO与衬底之间界面的质量。在本文中，我们报告了使用金属有机化学气相沉积（MOCVD）技术在R面蓝宝石衬底上生长的外延（1120）ZnO薄膜的压电性能研究。ZnO薄膜的c轴在平面内。ZnO/R-Al₂O₃界面在原子尺度上很清晰。与c轴平行排列的SAW延迟线被用于表征表面波速度、耦合系数以及频率温度系数与膜厚与波长比（h/λ）的函数关系。使用阿德勒矩阵方法计算了材料系统的声波特性，并基于格林函数分析使用准静态近似对器件进行了模拟。
