Characterising thermal resistances and capacitances of GaN high-electron-mobility transistors through dynamic electrothermal measurements

This study presents a method to characterise thermal resistances and capacitances of GaN high-electron-mobility transistors (HEMTs) through dynamic electrothermal measurements. A measured relation between RF gain and the channel temperature (T_c) is formed and used for indirect measurements of dynamic T_c responses. Thermal resistances and capacitances are characterised on the basis of measured T_c responses and power dissipation (P_d) in HEMTs. The proposed method makes it possible to measure fast T_c responses and avoids the use of imaging and spectroscopy techniques. Additionally, the proposed method ensures that trapping effects have insignificant impact on the measurements of T_c responses, which makes this method suitable for GaN HEMT characterisation. The applicability of this method is demonstrated by characterising thermal resistances and capacitances of a CREE CGH40006P GaN HEMT.