Electrically tunable GHz acoustic waveguide using Al0.7Sc0.3N thin film

Abstract

This Letter introduces an innovative electrically tunable suspended acoustic waveguide utilizing aluminum scandium nitride thin film. This design allows for dynamic modulation of the phase of traveling acoustic waves through the application of a vertical electric field. With both simulation and experimental approaches, the study explores how the waveguide width and inherent dispersion properties influence phase modulation. Results indicate that broader waveguides demonstrate more significant phase lag, with phase shifts of 37.2°, 40.8°, and 44.7° for waveguide widths of 10, 20, and 30 μm, respectively, measured in 200 μm-long segments under a ±40 V DC bias at 1.05 GHz. The exceptionally low Vπ·L of 6.44 V·cm underscores the system's ability to control phase efficiently with minimal power consumption. The exceptional properties of the waveguide make it a promising candidate for advanced acoustic signal processing, enabling precise phase control to enhance both device performance and energy efficiency.