Acoustic delay lines to measure piezoelectricity in 4H silicon carbide

This paper reports the first measurement of the electromechanical coupling coefficient (K
²
) for the Rayleigh wave in 4H polytype of Silicon Carbide (SiC). We fabricate 18 acoustic delay lines on two 4H SiC chips. Transmitted acoustic signals are measured at 423 MHz and 676 MHz for devices with 16 μm and 10 μm wavelength, respectively. We post-process the transmitted signal in time-domain to isolate the surface acoustic wave transmission. From the filtered signals we extract K
²
to be (0.93±0.05) x10
^-4
% and (0.66±0.02) x10
^-4
% at 423 MHz and 676 MHz.