Operation up to 500 °c of Al<inf>0.85</inf>Ga<inf>0.15</inf>N/Al<inf>0.7</inf>Ga<inf>0.3</inf>N high electron mobility transistors

AlGaN channel high electron mobility transistors (HEMTs) are the potential next step after GaN channel HEMTs, as the high aluminum content channel leads to an ultra-wide bandgap, higher breakdown field, and improved high temperature operation. Al0.85Ga0.15N/Al0.7Ga0.3N (85/70) HEMTs were operated up to 500 °C in ambient causing only 58% reduction of dc current relative to 25 °C measurement. The low gate leakage current contributed to high gate voltage operation up to +10 V under Vds = 10 V, with ION/IOFF ratios of > 2 × 1011 and 3 × 106 at 25 and 500 °C, respectively. Gate-lag measurements at 100 kHz and 10% duty cycle were ideal and only slight loss of pulsed current at high gate voltages was observed. Low interfacial defects give rise to high quality pulsed characteristics and a low subthreshold swing value of 80 mV/dec at room temperature. Herein is an analysis of AlGaN-channel HEMTs and their potential future for high power and high temperature applications.