High Quality Factors in Superlattice Ferroelectric Hf 0.5 Zr 0.5 O 2 Nanoelectromechanical Resonators.

The discovery of ferroelectricity and advances in creating polar structures in atomic-layered hafnia-zirconia (Hf x Zr 1- x O 2 ) films spur the exploration of using the material for novel integrated nanoelectromechanical systems (NEMS). Despite its popularity, the approach to achieving high quality factors ( Q s) in resonant NEMS made of Hf x Zr 1- x O 2 thin films remains unexplored. In this work, we investigate the realization of high Q s in Hf 0.5 Zr 0.5 O 2 nanoelectromechanical resonators by stress engineering via the incorporation of alumina (Al 2 O 3 ) interlayers. We fabricate nanoelectromechanical resonators out of the Hf 0.5 Zr 0.5 O 2 -Al 2 O 3 superlattices, from which we measure Q s up to 171,000 and frequency-quality factor products ( f × Q ) of >10 11 Hz through electrical excitation and optical detection schemes at room temperature in vacuum. The analysis suggests that clamping loss and surface loss are the limiting dissipation sources and f × Q > 10 12 Hz is achievable through further engineering of anchor structure and built-in stress.