AlScN Contour-Mode Resonators With Electromechanical Coupling in Excess of 4.5.

In this paper, we demonstrate the fabrication of contour-mode resonators (CMRs) with AlScN as a piezoelectric layer. Moreover, we assess the electromechanical coupling and the maximum achieved quality factor from 150 to 500 MHz. In comparison to pure aluminum nitride (AlN) CMRs, our results show electromechanical coupling coefficients of more than a 2× factor higher at around 200 MHz. The highest quality factor is measured on a CMR operating at 388 MHz and is in excess of 1600. From the characterization of devices operating at different frequencies, material parameters of the AlScN are extracted such as the stiffness constant, the relative permittivity, and the piezoelectric constant. In particular, the reported d piezoelectric constant is equal to -3.9 pm/V. This represents a 2.25× improvement when compared to pure AlN. Finally, we report the first temperature compensation experimental results for AlScN CMRs. Our results show that about 1.5 [Formula: see text] of sputtered oxide, deposited on top of a released resonator, allows near zero temperature coefficient of frequency variation for CMRs operating up to 500 MHz.