Stable Operation of AlGaN/GaN HEMTs at 400$^\circ$C in air for 25 hours

TL;DR

This study demonstrates the stable operation of AlGaN/GaN HEMTs with Pd gates in air at temperatures up to 500°C over 25 hours, highlighting their potential for high-temperature applications.

Contribution

First comprehensive analysis of AlGaN/GaN HEMTs stability at high temperatures in air over extended periods, including degradation mechanisms at 500°C.

Findings

Stable threshold voltage variation (<1%) from 22°C to 500°C

Operational stability of devices at 400°C for 25 hours

Degradation at 500°C linked to 2DEG density and mobility decrease

Abstract

In this letter, we report the operation of AlGaN/GaN HEMTs with Pd gates in air over a wide temperature range from 22$^\circ$C to 500$^\circ$C. The variation in the threshold voltage ($V_{th}$) is less than 1$\%$ over the entire temperature range. Moreover, a safe biasing region where the transconductance peak ($g_m$) occurs over the entire temperature range was observed, enabling high-temperature analog circuit design. Furthermore, the operation of the devices over 25 hours was experimentally studied, demonstrating the stability of the DC characteristics and $V_{th}$ at 400$^\circ$C. Finally, the degradation mechanisms of HEMTs at 500$^\circ$C over 25 hours of operation are discussed, and are shown to be associated with the 2DEG sheet density and mobility decrease.