The recent discovery of ferroelectricity in wurtzite scandium-aluminum-nitride (ScAlN) has opened a wide range of opportunity for creation of novel III-V microsystems. ScAlN provides various unique features including ferroelectric polarization switching, large piezoelectric coupling, and the feasibility of lattice-matched growth on GaN. These enable engineering microsystems created from monolithic integration of ScAlN resonators or memory devices with GaN electronics. Such microsystems can potentially revolutionize the high-power and high-frequency RF chips by adding new functionalities such as high quality-factor mechanical resonance and nonvolatile information storage and digital processing.
We are exploring ScAlN films, grown by reactive magnetron sputtering, to identify their optimized manufacturing process, and to understand their fundamental ferroelectric, piezoelectric, and dielectric properties. Besides, we are engineering novel microsystems, through integration of ScAlN films on AlGaN-GaN platforms to realize monolithic frequency references and fron-end modules. This research thrust is supported by DARPA, NASA / JPL, and industry projects.
- Rassay, D. Mo, C. Li, N. Choudhary, C. Forgey, and R. Tabrizian, “Intrinsically Switchable Ferroelectric Scandium Aluminum Nitride Lamb-Mode Resonators,” in IEEE Electron Device Letters, vol. 42, no. 7, pp. 1065-1068, July 2021.
- Rassay, F. Hakim, C. Li, C. Forgey, and R. Tabrizian, “A segmented-target sputtering process for growth of sub-50 nm ferroelectric scandium aluminum nitride films with composition and stress tuning,” Physica Status Solidi RRL, vol. 15, no. 5, p. 2100087, April 2021.
- Ghatge, M. Rais-Zadeh, and R. Tabrizian, “High-Q Gallium Nitride Thickness-Shear Baw Resonators with Reduced Temperature Sensitivity,” 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), 2021, pp. 1400-1403.