Stable Operation of AlGaN/GaN HEMTs for 25 h at 400°C in air

Abstract

Extreme environments such as the Venus atmosphere are among the emerging applications that demand electronics that can withstand high-temperature oxidizing conditions. While wide-bandgap technologies for integrated electronics have been developed so far, they either suffer from gate oxide and threshold voltage ( $V_{th}$ ) degradation over temperature, large power supply requirements, or intrinsic base current. In this letter, AlGaN/GaN high electron mobility transistors (HEMTs) are suggested as an alternative platform for integrated sensors and analog circuits in extreme environments in oxidizing air atmosphere over a wide temperature range from 22°C to 400°C. An optimal biasing region, with a peak of transconductance ( $g_{m,peak}$ ) at −2.3 V with a negligible shift over the temperature range was observed. Moreover, remarkably low $V_{th}$ variation of 0.9% was observed, enabling the design of analog circuits that can operate over the entire temperature range. Finally, the operation of the devices at 400°C and 500°C over 25 hours was experimentally studied, demonstrating the stability of the DC characteristics after the 5 hours of burn-in, at 400°C.