Effective electromechanical coupling coefficient ( keff2 ) enhancement of a Lamb wave resonator with trapezoid grooves configuration
Yuchen Fan, Jie Zhou, Qinwen Xu, Xin Tong, Ying Xie, Yang Zou, Jiaqi Ding, Chao Gao, Binghui Lin, Wenjuan Liu, Yan Liu, Yao Cai, Chengliang Sun
Abstract
Abstract A first-order ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:math> ) Lamb wave resonator (LWR) with a trapezoid grooves configuration on the top surface of the aluminum nitride membrane between interdigital electrodes is proposed in this paper. Both the simulation and experiment results demonstrate that the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>k</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> can be enhanced with the depth of the trapezoid grooves increasing. Meanwhile, the spurious modes can be suppressed by the trapezoid grooves. A 75% improvement on the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>k</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> has been achieved in a 2.45 GHz <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:math> mode LWR with trapezoid grooves with spurious modes free. The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>k</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> reaches up to 5.47% without quality factor degradation.