This paper demonstrates super high frequency (SHF) Lamb and surface acoustic wave resonators based on single-crystal orientation Aluminum Scandium Nitride (AlScN) thin films grown on silicon substrates by molecular beam epitaxy (MBE). We report on the experimental frequency response and electromechanical properties of 400 nm-thick crystalline AlScN acoustic resonators with up to 12% Sc/(Sc+Al) ratio. The film thickness is optimized for operation at the SHF range, targeting emerging wireless communication standards, such as 4G LTE/5G. We report on high-performance acoustic devices that take advantage of the crystallinity, and high piezoelectric properties of 400 nm-thick epitaxial AlScN films. Our work presents enhanced effective electromechanical coupling coefficients ( $k_{eff}^{2}$ ) up to 5.3% and unloaded quality factors ( $Q_{m}$ ) of ~192 at 3–10 GHz. However, fabrication challenges due to the high-stress levels of sub-micron AlScN epi-layers grown on Si substrates remain challenging and will be discussed in this paper. [2019-0231]

中文翻译：

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外延铝氮化钪超高频声波谐振器

本文展示了基于通过分子束外延 (MBE) 在硅衬底上生长的单晶取向氮化铝钪 (AlScN) 薄膜的超高频 (SHF) Lamb 和表面声波谐振器。我们报告了 Sc/(Sc+Al) 比率高达 12% 的 400 nm 厚结晶 AlScN 声谐振器的实验频率响应和机电特性。薄膜厚度针对 SHF 范围内的操作进行了优化，针对新兴的无线通信标准，例如 4G LTE/5G。我们报告了利用 400 nm 厚外延 AlScN 薄膜的结晶度和高压电特性的高性能声学器件。我们的工作提出了增强的有效机电耦合系数（ $k_{eff}^{2}$ ) 高达 5.3% 和卸载质量因素 ( $Q_{m}$ ) 在 3–10 GHz 时约为 192。然而，由于在 Si 衬底上生长的亚微米 AlScN 外延层的高应力水平导致的制造挑战仍然具有挑战性，并将在本文中进行讨论。[2019-0231]