Tunable and switchable film bulk acoustic resonators (FBARs) with the capability of dynamically adjusting their resonant frequencies hold significant promise for advanced multi‐band radio frequency (RF) communication systems. However, tunable and switchable FBARs based on conventional thin ferroelectric materials face several challenges in meeting the demands of advanced RF applications. Specifically, submicron‐thick ferroelectric materials suffer from degradation in piezoelectric performance due to the strong scattering of acoustic waves caused by surface defects, as well as the inconsistency in crystal orientation. Recent advances in 2D ferroelectric materials create new opportunities for high‐performance tunable and switchable FBARs. Here, the first batch of FBAR chips based on 2D α‐In2Se3 flakes is reported. The α‐In2Se3‐based FBARs are normally under the on‐state and possess a small off‐voltage of −4 V. A tuning range of 26 MHz is achieved with a control voltage from −2 to 4 V at the resonant frequency of 8.6 GHz. To the best of the author's knowledge, this is the first batch of tunable FBARs that can function beyond the sub‐6 GHz band. This work demonstrates for the first time that 2D ferroelectric materials are very promising for high‐frequency tunable and switchable FBARs.

中文翻译：

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用于高频可调谐和可切换薄膜体声波谐振器的 2D α-In2Se3 薄片


可调谐和可切换的薄膜体声谐振器 （FBAR） 具有动态调整其谐振频率的能力，在先进的多频段射频 （RF） 通信系统中具有重要前景。然而，基于传统薄铁电材料的可调谐和可切换 FBAR 在满足高级射频应用的需求方面面临一些挑战。具体来说，由于表面缺陷引起的声波强烈散射以及晶体取向的不一致，亚微米厚的铁电材料会受到压电性能下降的影响。2D 铁电材料的最新进展为高性能可调谐和可切换 FBAR 创造了新的机会。本文报道了第一批基于 2D α-In2Se3 薄片的 FBAR 芯片。基于 α-In2Se3 的 FBAR 通常处于导通状态，并具有 −4 V 的小关断电压。在 8.6 GHz 谐振频率下，通过 −2 至 4 V 的控制电压实现 26 MHz 的调谐范围。据作者所知，这是第一批可以在 sub-6 GHz 频段之外工作的可调谐 FBAR。这项工作首次证明 2D 铁电材料在高频可调谐和可切换 FBAR 方面非常有前途。