IEEE Trans Ultrason Ferroelectr Freq Control. 2022 Aug;69(8):2579-2584. doi: 10.1109/TUFFC.2022.3179699. Epub 2022 Jul 29.
This article presents shear horizontal surface acoustic wave (SH-SAW) devices with excellent temperature stability and low loss on ultrathin Y42-cut lithium tantalate film on sapphire substrate (LiTaO-on-sapphire, LTOS). The demonstrated resonators exhibit scalable resonances from 1.76 to 3.17 GHz, effective electromechanical coupling coefficients between 5.1% and 7.6%, and quality factors (Bode-Q) between 419 and 3019. The filter with a center frequency of 3.26 GHz features a suppressed spurious passband, a 3-dB fractional bandwidth (FBW) of 3%, and a minimum insertion loss (IL) of 2.39 dB. In addition, coplanar waveguides (CPWs) and SH-SAW resonators built on LTOS and LiTaO-on-insulator (LTOI) substrates were compared over a temperature range of 25 °C-150 °C. Due to the extremely high resistivity of the sapphire and the excellent thermal stability of the LiTaO/sapphire interface, the IL of the CPW and the impedance ratio (in addition to Bode-Q) of the SH-SAW on the LTOS are maintained well even at 150 °C, while those on the LTOI seriously deteriorate. Of these, the impedance attenuation of LTOS-SAW at the antiresonant frequency is only 3.7 dB at 150 °C, whereas that of LTOI-SAW reaches 9.6 dB, demonstrating excellent temperature stability of the LTOS substrate's radio frequency (RF) performance. Overall, the SAW devices on LTOS substrates show great potential for temperature-sensitive and low-loss applications in RF wireless communications.
本文展示了在蓝宝石衬底上的超薄 Y42 切型钽酸锂薄膜（LiTaO-on-sapphire，LTOS）上具有出色温度稳定性和低损耗的剪切水平表面声波（SH-SAW）器件。所展示的谐振器具有可扩展的共振频率范围，从 1.76GHz 到 3.17GHz，有效机电耦合系数在 5.1%到 7.6%之间，品质因数（Bode-Q）在 419 到 3019 之间。中心频率为 3.26GHz 的滤波器具有抑制的寄生通带，3dB 带宽（FBW）为 3%，最小插入损耗（IL）为 2.39dB。此外，在 25°C-150°C 的温度范围内，对 LTOS 和 LiTaO-on-insulator（LTOI）衬底上的共面波导（CPW）和 SH-SAW 谐振器进行了比较。由于蓝宝石的极高电阻率和 LiTaO/蓝宝石界面的出色热稳定性，即使在 150°C 时，LTOS 上 CPW 的 IL 和 SH-SAW 的阻抗比（除了 Bode-Q 之外）也保持良好，而 LTOI 上的则严重恶化。其中，LTOS-SAW 在反谐振频率处的阻抗衰减在 150°C 时仅为 3.7dB，而 LTOI-SAW 达到 9.6dB，表明 LTOS 衬底的射频（RF）性能具有出色的温度稳定性。总体而言，LTOS 衬底上的 SAW 器件在 RF 无线通信中具有很大的潜力，可用于对温度敏感和低损耗的应用。
