Self-heating effect on device characteristics of GaN/AlGaN HEMTs: 2D Monte Carlo device simulation

Mechanism of self-heating in GaN/AlGaN HEMT and an influence of lattice-temperature rise on device characteristics are investigated theoretically. A novel simulation technique is applied, where a local temperature-dependent carrier transport is calculated by employing a Monte Carlo (MC) particle technique in combination with a heat flow calculation. The devices on substrates of three different materials, i.e., silicon carbide (SiC). sapphire (Al₂O₃) and silicon (Si), are studied and compared. A heat generation concentrates on the drain side of the area under gate, which is mainly coming from intra-valley scatterings of electrons in Γ₁ and U valleys under high electric field. It is suggested that the SiC and the Si substrates are of great advantage to reduction of the self-heating effect on device characteristics because of their higher thermal conductivities, in comparison with the Al₂O₃ substrate.