Design and Fabrication of Phononic Integrated Circuits in Scandium Aluminum Nitride

Acoustic waves are well-suited for a variety of signal processing applications including RF filtering and optical modulation. Advances in material and fabrication capabilities have enabled the demonstration of chip-scale subsystems in which phonons can exhibit strong interactions with a variety of other physical domains. To this end, the guidance and control of acoustic waves in phononic integrated circuits enables numerous opportunities. This talk focuses on the development of such guided surface acoustic wave components in solidly mounted 30% scandium-doped aluminum nitride (ScAlN). Numerical modeling, coupled with experimental results, showcases the characteristics of focusing interdigitated transducers (FIDTs) for injecting acoustic energy into piezoelectric etch-defined acoustic waveguides and highlights their advantages over conventional uniform aperture transducers. We also demonstrate the behavior of 90-degree bends, low-loss Y-junctions as splitters/combiners and directional couplers to enable phononic integrated circuit applications in slow-on-fast piezoelectric platforms.