TOPOLOGICALLY PROTECTED FANO RESONANCE IN A 80 MHZ SC-DOPED ALN THIN FILM RESONATOR WITH A QUALITY FACTOR LARGER THAN 10K

In this study, we introduce the first-ever AlScN resonant device able to excite a topologically protected mode of vibration. This device operates at 80 MHz, and it leverages the strong piezoelectricity of AlScN films using a 30% scandium doping concentration. By utilizing a combination of finite element simulations and experimental data, we demonstrate that the interconnection of two suspended metamaterials exhibiting distinct topological characteristics enables the generation of localized acoustic resonances. The destructive interference between two of these resonances creates a mechanical anti-resonance frequency with modal energy constrained within a 15 µm distance around the interface, following the physics of topologically protected Fano resonances. We show that the device’s quality factor at this anti-resonance frequency reaches a value (>10,000) much higher than anything else ever reported for thin-film AlScN devices not attached on silicon, silicon carbide, or other low-loss materials. The device reported in this work opens exciting opportunities to use AlScN MEMS for sensing a variety of parameters of interest with exceptional spatial sensing resolution, sensitivity, and limit-of-detection.