Thermal behavior analysis of GaN based epi-material on different substrates by means of a physical-thermal model
Résumé
For gallium nitride (GaN) based microwave power devices, the thermal behavior due to the self-heating effect constitutes a main limitation because the power dissipation is very high. For this study, a predictive physical-thermalmodel has been developed to analyze the physical and thermal phenomena observed in experiment. In this paper, the thermal performances of AlGaN/GaN epitaxies grown on different substrates are determined. It is found that compared with Si substrate, composite substrates: SopSiC (mono-Si/poly-SiC) and SiCopSiC (mono-SiC/poly-SiC) substrates (V. Hoel et al., Electron. Lett. 44, 238 (2008) [1] and T.J. Anderson et al., J. Vac. Sci. Technol. B 24, 2302 (2006) [2]) present better thermal resistances especially at high dissipated power densities with an improvement of 18% for SopSiC substrate and 25% for SiCopSiC substrate at 12W/mm. Furthermore, polycrystalline diamond is the most promising substrate with a thermal resistance of 5.4W/mK at 12W/mm. The simulation results, such as lattice temperature and thermal resistance, are in good agreement with ourmeasurements.