Didenko I S, Hickernell F S, Naumenko N F
Crystal Physics Department, Moscow Steel and Alloys Institute, Moscow, Russia.
IEEE Trans Ultrason Ferroelectr Freq Control. 2000;47(1):179-87. doi: 10.1109/58.818760.
The surface acoustic wave (SAW) propagation properties of zinc oxide (ZnO) films on silicon carbide (SiC) have been theoretically and experimentally characterized in the film thickness-to-acoustic wavelength ratio range up to 0.12. The experimental characterization of the SAW propagation properties was performed with a linear array of interdigital transducer (IDT) structures. The measurements characterized the velocity and propagation loss of two surface modes, a generalized SAW (GSAW) mode with velocities between 6000 and 7000 m/s, and a high velocity Pseudo-SAW (HVPSAW) mode with velocities between 8500 and 12 500 m/s. The experimentally determined characteristics of the two waves have been compared with the results of calculations based on published data for SiC and ZnO. Simulation of wave characteristics was performed with various values of the elastic constant C(13), which is absent in the published set of material constants for SiC, within the interval permitted by the requirement of positive elastic energy in a hexagonal crystal. The best agreement between the measured and calculated propagation losses of the HVPSAW has been obtained for C(13) near zero. Although for the GSAW mode the calculated velocity dispersion has been found nearly insensitive to the value of C (13) and consistent with the experimental data, for the HVPSAW, some disagreement between measured and calculated velocities, which increased with ZnO film thickness, has been observed for any C(13 ) value. Theoretical analysis of HVPSAW has revealed the existence of a previously unknown high velocity SAW (HVSAW). The displacement components of this wave have been analyzed as functions of depth and confirmed its pure surface, one-partial character.
在高达0.12的膜厚与声波波长比范围内，对碳化硅（SiC）上氧化锌（ZnO）薄膜的表面声波（SAW）传播特性进行了理论和实验表征。SAW传播特性的实验表征是通过叉指换能器（IDT）结构的线性阵列进行的。测量表征了两种表面模式的速度和传播损耗，一种是广义SAW（GSAW）模式，速度在6000至7000 m/s之间，另一种是高速伪SAW（HVPSAW）模式，速度在8500至12500 m/s之间。已将实验确定的这两种波的特性与基于已发表的SiC和ZnO数据的计算结果进行了比较。在六方晶体中弹性能量为正的要求所允许的区间内，使用弹性常数C(13)的各种值对波特性进行了模拟，而在已发表的SiC材料常数集中没有C(13)。对于接近零的C(13)，获得了HVPSAW测量和计算传播损耗之间的最佳一致性。虽然对于GSAW模式，发现计算出的速度色散对C(13)的值几乎不敏感且与实验数据一致，但对于HVPSAW，对于任何C(13)值，都观察到测量和计算速度之间存在一些差异，且这种差异随ZnO薄膜厚度增加而增大。对HVPSAW的理论分析揭示了一种先前未知的高速SAW（HVSAW）的存在。已分析了该波的位移分量随深度的变化，并证实了其纯表面、单部分特性。
