ScAlN/AlN Film-Based Lamé Mode Resonator With High Effective Electromechanical Coupling Coefficient
Jie Zhou, Yan Liu, Qinwen Xu, Ying Xie, Yao Cai, Jieyu Liu, Wenjuan Liu, Alexander Tovstopyat, Chengliang Sun
Abstract
The effective electromechanical coupling coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{eff}^{2}{)}$ </tex-math></inline-formula> of resonators is crucial for application in radio communication such as fabricating bandpass filters. In this letter, we present a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0^{\text {th}}$ </tex-math></inline-formula> symmetry ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{0}{)}$ </tex-math></inline-formula> mode Lamé mode resonator (LMR) operating at 2.563 GHz with a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{\vphantom {D_{j}}{eff}}^{2}$ </tex-math></inline-formula> of 7.83%. A 20% Scandium-doped Aluminum Nitride (Sc <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> N)/AlN composite piezoelectric film is used as the piezoelectric layer. The ratio of piezoelectric layer thickness ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}_{\vphantom {D_{j}}{pie}}{)}$ </tex-math></inline-formula> and electrode pitch ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{ele}{)}$ </tex-math></inline-formula> is optimized by finite element analysis (FEA) method and the highest experimental <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}_{eff}^{2}$ </tex-math></inline-formula> is obtained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}_{pie}/{P}_{ele} =0.65$ </tex-math></inline-formula> . The proposed LMR with Sc doping and structural optimization shows fascinating prospects for constructing broadband filters. [2021-0113]