Temperatures at GaNHETs

Temperatures at GaN HFETs can reach as high as 330°C locally according to finite element analysis conducted at the University of South Carolina.  The infrared imaging system at TPUC was used to study this device. A Ge microscope lens at TPUC gives a spatial resolution of 5.4 µm per pixel. The device was wire-bonded and energized by a DC power supply. Up to 15 V was applied to the gate (GaN strip). Temperature change as a function of time was recoded. The device temperature was found to be around 150-180°C depending on the gate structure.  Since the actual area of the HFET is on the order of a few microns, 5.4µm resolution may have only collected the average temperature of that area. The modeling result of over 300°C local temperature is possible.  Localized cooling may be needed for the HFET devices.