Design and Performance of ScAlN/AlN Trapezoidal Cantilever-Based MEMS Piezoelectric Energy Harvesters

Abstract

In this work, we report a method to enlarge the trapezoidal cantilever-based harvester power by using the high-performance Sc <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> N/aluminum nitride (AlN) composite film and introducing symmetrical corners to both sides of the beam. Energy harvesters with variable beam structure and piezoelectric film are designed and evaluated by simulations and experiments. The trapezoid with corners (TWCs) cantilever is verified to improve the output power by a factor of five times when compared with the conventional trapezoidal cantilever without corners. The maximum power density of the ScAlN/AlN-based TWC cantilever harvester is about twice that of the AlN-based harvester, reaching 2.054 mW ·g <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> at a frequency of 330.25 Hz. The optimization of piezoelectric film and structure can give an inspiration for further improving the performance of cantilever-based energy harvesters.