We grow carbon nanotube forests on piezoelectric AlN films and fabricate and characterize nanotube-based solidly mounted bulk acoustic wave resonators employing the forests as the top electrode material. The devices show values for quality factor at anti-resonance of ∼430, and at resonance of ∼100. The effective coupling coefficient is of ∼6%, and the resonant frequencies are up to ∼800 MHz above those observed with metallic top electrodes. AlN promotes a strong catalyst-support interaction, which reduces Fe catalyst mobility, and thus enforces the growth of forests by the base growth mechanism.
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