Characterization of an AlGaN/GaN Electrostatically Actuated Cantilever Using the Finite Element Method

N. DeRoller, M. Qazi, J. Liu, and G. Koley
University of South Carolina, Columbia, SC, USA

AlGaN/GaN heterostructures are unique because the 2DEG at the interface is created by the difference in polarization properties of the AlGaN and the GaN layers; not due to intentional doping. In this work, a 3D model of an electrostatically actuated micro cantilever has been developed using COMSOL for characterization using the finite element method (FEM). The microcantilever has AlGaN/GaN HFET embedded on its base. Through various FEM simulations we are able to determine its operating frequency, electrostatic response, and strains about the AlGaN/GaN interface. The complex, asymmetric top geometry of this structure makes 3D FEM simulation more desirable over standard PDE based analysis. Simulations were run to observe electrostatic deflection given a sinusoidal voltage input. Also, we measured strains along the length of the HFET located near the base while a normal downward force is acting on the tip. Measuring these strains will help us determine current change in the AlGaN/GaN HFET due to its piezoelectric properties.