Evaluation of the Schottky Contact Degradation on the Temperature Transient Measurements in GaN HEMTs

The temperature dependence of the Schottky voltage under a forward constant current was used as a means to measure the transient temperature characteristics of gallium nitride (GaN) high-electron-mobility transistors (HEMTs). However, the degradation of the Schottky diode leads to error in the calculated temperature measurement results, especially at a high forward Schottky current. In this paper, we characterized the degradation of GaN HEMT Schottky diodes under forward bias using pulsed current-voltage measurements. The forward Schottky voltage behavior at constant currents of 0.2, 0.35, 0.5, 1, 1.5, and 2 mA was monitored. In particular, the vertical temperature distribution was corrected experimentally based on the transient voltage measurements. The success of this correction indicates that the said artifacts can be removed using the transient voltage measurements. This method increases the accuracy of temperature measurements when the temperature dependence of the Schottky voltage is used to characterize the behavior of GaN HEMTs.