A mechanism of self-heating in GaN/AlGaN HEMT and an influence of lattice-temperature rise on device performance 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., sapphire, silicon carbide (SiC), and silicon (Si) are studied and compared. The heat generation concentrates on a drain side of area under a gate, which is mainly coming from intra-valley scatterings of electrons in Γ1 and U valleys under a 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 performance because of their higher thermal conductivities, in comparison with the sapphire substrate. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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Fujishiro et al. (2005) studied this question.