High Crystalline Quality A-Axis Oriented Al0.56Sc0.44N Films for High Coupling Saw Applications

High crystalline quality Al 0.56 Sc 0.44 N $\left( {11\bar 20} \right)$ (a-plane) films were prepared on Al 2 O 3 $\left( {1\bar 102} \right)$ substrates by magnetron reaction sputtering. X-ray diffraction (XRD) analysis indicates that the grown Al 0.56 Sc 0.44 N films are single-phased and a-plane oriented. The full width at half maximum (FWHM) of the rocking curve is only 0.4°, showing the high crystalline quality of the films. Effects of the normalized thickness h AlScN /λ on the acoustic wave propagation properties of the SAW resonator are evaluated by simulations. SAW resonators based on the sputtered non-polar $\left( {11\bar 20} \right)$ Al 0.56 Sc 0.44 N films were prepared, which present a maximum electromechanical coupling coefficient $\left( {k_{eff}^2} \right)$ of 5.7%.