High Resolution Thermoreflectance Imaging and Numerical Modeling of Self-Heating in GaN HEMT on SiC

Gallium Nitride (GaN) based high-power devices require advance thermal analysis to ensure that the operating temperature is kept within a reliable range. High conductivity substrates such as Silicon Carbide (SiC) are used instead of Silicon (Si) to increase the thermal conductance from the device structure. This study observes the self-heating in GaN-SiC HEMTs using high-resolution thermoreflectance imaging. A verification with multi-grid self-adaptive modeling shows a dynamic power generation profile that changes from low to high activation levels. The method allows to estimate the heat generation profile in the GaN HEMT from the observed temperature rise profile across the GaN channel, which is crucial to understand the heat generation regime and develop an accurate thermal model for the GaN HEMTs.