Variable thermal resistance model of GaN-on-SiC with substrate scalability

Abstract

A drain current model for an AlGaN/GaN high-electron-mobility transistor (HEMT) with variable thermal resistance is developed. For the first time, a variable thermal resistance in terms of the substrate thickness $$(t_{\text{SiC}} )$$ is included rather than a constant thermal resistance. One of the distinguishing features of this model is that it is scalable with substrate thickness. The compact drain current model is compared with simulated characteristics for different substrate thicknesses (tSiC = 100 μm, tSiC = 200 μm, and tSiC = 300 μm). The proposed model clearly captures the self-heating effect well in the saturation region of the drain current at an ambient temperature of 300 K. The transfer and transconductance characteristics of the model show good correlations with both experimental and simulation data under a wide range of bias conditions. Furthermore, the smoothness of the model is confirmed by Gummel symmetry and continuity tests. Hence, the proposed model is compact and considered to be a promising candidate for GaN-HEMT circuit simulation.