Investigation on thermo-mechanical responses in high power multi-finger AlGaN/GaN HEMTs

Abstract

Both transient temperature and thermal stress responses in high power multi-finger AlGaN/GaN high electron mobility transistors (HEMTs), caused by their self-heating effects, are characterized in the present study. Instead of using commercial software, self-developed algorithm based on hybrid time-domain finite element method (TD-FEM) is applied for thermo-mechanical co-simulation of such 3-D structure. The temperature-dependent properties of most constitutive parameters of all materials involved, in particular for electrical conductivities, thermal conductivities, thermal expansion coefficients, and Young’s modulus, are described by several sets of nonlinear polynomial expressions. The algorithm accuracy is validated in detail, with good agreement achieved in comparison with the commercial software COMSOL. It is believed that this study will be useful for effectively evaluating the reliability and lifetime of AlGaN/GaN HEMTs and their monolithic microwave integrated circuits (MMIC) used in high power communication systems and radars.