High Resolution Thermal Characterization and Simulation of Power AlGaN/GaN HEMTs Using Micro-Raman Thermography and 800 Picosecond Transient Thermoreflectance Imaging

Self-heating in gallium nitride based high frequency, high electron mobility power transistors (GaN HEMTs) is inspected using micro-Raman thermography and 800 picosecond transient thermoreflectance imaging. The two methods provide complementary temperature information inside the semiconductor and on top metal layers of the GaN HEMT. Self heating is measured under both steady-state and ultra-fast pulsed transient operation with submicron spatial resolution, 50 milliKelvin temperature resolution, and nanosecond time resolution. Fine grain electrothermal modeling of the HEMT steady state and transient self-heating are presented alongside measurements. Large spatial and temporal temperature gradients are quantified. Deviations due to unknown parameters are discussed.