Ultra thin AlN piezoelectric nano-actuators

This paper reports the first implementation of ultra thin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nano-actuators. An average piezoelectric coefficient (d₃₁~ - 1.9 pC/N) that is comparable to its microscale counterpart has been demonstrated in nanoscale thin AlN films. Vertical deflections as large as 40 nm have been obtained in 18 mum long and 350 nm thick cantilever beams under bimorph actuation with 2 V. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. Leakage current lower than 2 nA/cm² at 1 V has been recorded and an average relative dielectric constant of approximately 9.2 (as in thicker films) has been measured. These material characteristics and preliminary actuation results make the AlN nano-films ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.