Determination of the channel temperature in GaN MOSHFETs under microwave operational conditions

In this work, we present a method to extract the device channel temperature of AlGaN/GaN metal-oxide-semiconductor hetero structure field effect transistors(MOSHFETs) in time domain under continuous wave (CW) and periodic-pulsed RF (radiation frequency) operational conditions. The temporal profiles of microwave output power densities of GaN MOSHFETs were measured at 2 GHz under such conditions and used for the extraction of the channel temperature. The measurement technique in this work is also being utilized to extract the thermal time constant of the devices. Analytical temporal solutions of temperature profile in MOSHFETs are provided to support the extraction method. The analytical solutions can also apply to generic field effect transistors (FETs) with an arbitrary form of time-dependent heat input at the top surface of the wafer.