Work

Spurious-Mode Suppression in Sc0.2Al0.8N Film Lamb Wave Resonators and Filters with Arc-Shaped Apodization

Year: 2026

Type: article

Abstract: Lamb wave devices have the advantage of monolithic multi-frequency integration and show great application potential in mobile communications. However, their performance is often limited by spurious modes. In this work, an arc-shaped apodization electrode structure is proposed to suppress spurious modes in Sc0.2Al0.8N Lamb wave resonators (LWRs). By shortening the overlap length of the interdigital transducer electrodes at the edges, the energy coupling in the spurious-mode regions is reduced while the main-mode region is largely preserved. Finite element method (FEM) simulations confirm the suppression of spurious responses near the anti-resonant frequency. Based on the optimized design, typical and arc-shaped apodization LWRs and filters were fabricated. The fabricated arc-shaped apodization LWR exhibits an effective electromechanical coupling coefficient (keff2) of 3.9%. The corresponding filter operates at a center frequency of 1.774 GHz, with a −3 dB bandwidth of 20 MHz and a minimum insertion loss of 4.50 dB. Compared with the typical filter fabricated on the same wafer, the insertion loss is reduced by 1.22 dB. These results demonstrate the effectiveness of the proposed electrode apodization scheme for suppressing spurious modes in Sc0.2Al0.8N Lamb wave devices.

Source: Micromachines

DOI: 10.3390/mi17091046

Authors: Kai Cai, Haiyang Li, Tingting Yang, Qinwen Xu, Yao Cai

Institutions: Nanchang University, Wuhan University

Language: English

Topic: Acoustic Wave Resonator Technologies

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,534

Funders: China Postdoctoral Science Foundation, Wuhan University, Fundamental Research Funds for the Central Universities