Super High Frequency Aluminum Nitride Two-Dimensional-Mode Resonators With $k_{t}^{2}$ Exceeding 4.9%

In this work we demonstrate high values of electromechanical coupling coefficient (k
_t
²
) exceeding 4.9% in 1-μm thick Aluminum Nitride (AlN) two-dimensional-mode resonators (2DMRs) operating around 3.2 GHz. Such a high k
_t
²
-value, which is attained thanks to the transduction of the resonators through both the d
₃₃
and d
₃₁
piezoelectric coefficients of AlN, enables low-power oscillators and low insertion-loss filters, operating in the Super-High-Frequency (SHF) range.