Numerical simulation and compact modelling of AlGaN/GaN HEMTs with mitigation of self‐heating effects by substrate materials

In this paper, DC characteristics of an AlGaN/GaN on sapphire high-electron mobility transistor (HEMT) are measured, numerically simulated, and modelled accounting for self-heating effects (SHEs), with the main electrical parameters being extracted. Decomposing the transistor thermal resistance into the buffer and substrate components, our study can be easily extended to other substrate materials. Thus, sapphire is substituted with silicon, molybdenum, and SiC, which reduce current-collapse due to SHEs thanks to their considerably higher thermal conductivity, which improves transistor performance. Furthermore, we implement a compact model available for AlGaN/GaN HEMTs, incorporating the temperature dependence of extrinsic source/drain ohmic resistances, which are numerically evaluated for the different substrates.