Analytical and numerical modeling of AlGaN/GaN/AlN heterostructure based cantilevers for mechanical sensing in harsh environments

Abstract

Some industrial areas require functioning electronics in harsh environments. A solution is to use III-V materials alloys having semiconductor, piezoelectric and pyroelectric properties. These materials, particularly nitrides such as GaN or AlN, enable advanced design of devices suitable for harsh environment. A structure based on AlGaN/GaN/AlN cantilevers coupled with a High Electron Mobility Transistor (HEMT) can act as a mechanical sensing device suited to harsh environments. In this article, we present the mechanical modeling of such a device. An analytical and a numerical model have been developed to obtain the electrical charge distribution in the structure. A theoretical electromechanical sensitivity of around 3.5 μC.m−2 could be achieved for a displacement of several hundreds of nanometers. Both models agree considerably well, presenting less than 5% deviation on the whole structure, except near the clamped area, where differences can be explained by particular boundary conditions of the numerical model. The topological characterization and numerical modeling allowed the estimation of the equivalent intrinsic residual stress in the structure and the stress distribution within each layer. The obtained results enable the use of the analytical model for further study of the electromechanical coupling with the HEMT of the structure.