Temperature-Dependent Thermal Impedance Measurement of GaN-Based HEMTs Using Transient Thermoreflectance

The transient thermal response of GaN high-electron-mobility transistors (HEMTs) is studied using transient thermal thermoreflectance (TTR) measurements. The change in the thermal impedance at various ambient temperatures is observed and analyzed using finite-element (FE) simulation and thermal equivalent circuits. A temperature-dependent Cauer model has been implemented for predicting the transient temperature response of the device under test (DUT), applicable to arbitrary power dissipations or ambient temperatures. This work provides a practical way for determining or verifying transient thermal models of GaN-based HEMTs using RC networks.