Lithium Niobate Acoustic Resonators Operating Beyond 900 °C

In this paper, fundamental shear-horizontal <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$SH_{0}$</tex> mode Leaky Surface Acoustic Wave (LSAW) resonators on X-cut lithium niobate leveraging dense and robust electrodes such as gold and tungsten are demonstrated for extreme temperature operation in harsh environments. A novel post-processing approach based on in-band spurious mode tracking is introduced to enable reliable characterization under extreme parasitic loading during testing. Devices exhibit stable performance throughout multiple thermal cycles up to 1000 °C, with an extrapolated electromechanical coupling coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$k_{t}^{2}=25\%$</tex> and loaded quality factor <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{p}=12$</tex> at 1000 °C for tungsten devices, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$k_{t}^{2}=17\%,\ Q_{p}=100$</tex> at 900 °C for gold devices.