Epitaxial Single-Crystal ScAlN on 4H-SiC for High-Velocity, Low-Loss SAW Devices
Vikrant J. Gokhale, Brian P. Downey, Matthew T. Hardy, Eric N. Jin, J.A. Roussos, David J. Meyer
Abstract
This report presents some of the first experimental characterization of surface acoustic wave (SAW) devices using single-crystal ScAlN epitaxially grown on SiC. Due to the excellent wave guiding provided by the ScAlN/SiC heterostructure, SAW phase velocities greater than 12,000 m/s are measured, higher than comparable ScAlN SAW devices on other substrates. The phase velocity dispersion for measured devices compares well with simulated values. We observe up to k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> =0.52% even for very small thickness to wavelength ratios ( ). We show that epitaxial ScAlN/SiC can achieve extremely low SAW propagation loss ( ), comparable to state-of-the-art piezoelectric/diamond SAW devices, and are linear at CW RF power levels up to ≈30 dBm (1W), with 1 dB gain compression at 34 dBm and an IIP3 of 45 dBm.