Control of High-Frequency Surface Acoustic Waves via Transducer Geometry and Higher-Order Mode Equivalency.
basic_science · Level V
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- Record sourced from PubMed, PMID 42184205.
- Also identified by DOI 10.1021/acs.nanolett.6c01437.
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Abstract
GHz-range surface acoustic waves (SAWs) are essential for high-frequency sensing, hybrid photonic-phononic, and quantum devices. However, SAW generation via interdigital transducers (IDTs) on piezoelectric substrates faces significant scaling and attenuation challenges, besides being incompatible with silicon-based electronics due to the lack of piezoelectricity. Here, we demonstrate fundamental and higher-order SAW generation and detection in monolithic silicon using metallic transducers and time-resolved extreme ultraviolet diffraction measurements. Our results, supported by finite-element simulations, establish the equivalence of first- and second-order SAW frequencies (ν) and attenuation lifetimes (τ<sub>S</sub>) over wide ranges spanning 3.5-16.5 GHz and 14-0.6 ns, respectively, that allow high-frequency SAW generation with large τ<sub>S</sub> in the same device. We further show that τ<sub>S</sub> is tunable via transducer geometry, achieving second-order SAWs (2ν) near 10 GHz with τ<sub>S</sub> ≈ 5 ns. These findings reveal lower acoustic losses in silicon than those reported with IDTs on piezoelectric substrates.