ScAlN/AlN Film-Based Lamé Mode Resonator With High Effective Electromechanical Coupling Coefficient

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]