Extreme Temperature Operation of Ultra-Wide Bandgap AlGaN High Electron Mobility Transistors

摘要

High Aluminum content channel (Al0.85Ga0.15N/Al0.7Ga0.3N) High Electron Mobility Transistors (HEMTs) were operated from room temperature to 500 degrees C in ambient. The devices exhibited only moderate reduction, 58%, in on-state forward current. Gate lag measurements at 100 kHz and 10% duty only showed a slight reduction in pulsed current from DC at 500 degrees C and high gate voltages. Interfacial trap densities were 2x10(11) over the range 25-300 degrees C and 3x10(12) cm(-2) from 300-500 degrees C from the subthreshold swing. These low interfacial trap densities and the near ideal gate lag measurement indicate highquality epi layers. The insulating properties of the barrier layer led to low gate induced drain leakage current of similar to 10(-12) A/mm and similar to 10(-8) A/mm at 25 and 500 degrees C, respectively. Low leakage current was enabled by the high Schottky barrier of the Ni/Au gate, 1.1 eV and 3.3 eV at 25 and 500 degrees C, respectively. These properties of the AlGaN channel HEMTs demonstrate their potential for high power and high temperature operation.