Temperature test comparison of GaN devices under different light source responses based on thermoreflectance thermography

The thermoreflectance test technology is provided with high spatial and temporal resolution, which is suitable for temperature testing of tiny structures of GaN HEMTs (high electron mobility transistors). Based on the thermoreflectance thermography platform, this paper studies the response relationship between the thermoreflectance coefficient and wavelength of the passivated gold, unpassivated gold, and GaN on the surface of GaN HEMTs, and the differences in steady-state temperature distributions of passivated gold and unpassivated gold at different wavelengths are analyzed. The steady-state and transient temperature changes of the GaN HEMTs channel were tested, and their accuracy was verified using the finite element analysis simulation. Based on the established thermoreflectance coefficient distribution map, it can be seen that the passivated gold, unpassivated gold and GaN have good responses at wavelengths of 410 nm, 530 nm and 365 nm, respectively. For passivated gold and unpassivated gold, the temperature obtained at different wavelengths may have a difference of 20-40℃, and the wavelength with the best response can ensure the accuracy of the results. Due to the presence of the passivation layer, the temperature difference between the passivated gold and unpassivated gold reaches nearly 40℃ at a wavelength of 410 nm. Passivated gold and unpassivated gold need to be tested at 410 nm and 530 nm wavelengths in order to avoid the large temperature deviations.