Accurate Measurement of Channel Temperature for AlGaN/GaN HEMTs

This paper proposes a novel electrical method for the determination of channel temperature in AlGaN/GaN high-electron mobility transistors. A test structure combining various device geometries has been utilized to achieve the temperature dependence of the channel resistance and then applied to detect the channel temperature under the gate instead of that at the gate edge on the drain side. A 2-D electrothermal model has been built, and the model demonstrates excellent agreement with the experimental data. Compared with gate resistance thermometry and micro-Raman spectroscopy, our method has advantages of high accuracy, easy positioning, and immunity to the gate head geometry. This facilitates its potential for temperature extraction, especially for short channel devices. Finally, we apply this method to different device structures to demonstrate its scalability, and the uncertainty caused by current collapse is also discussed.