High-temperature effects of AlGaN/GaN high-electron-mobility transistors on sapphire and semi-insulating SiC substrates

TLDR

High‑temperature operation (≥300 °C) of HEMTs requires additional cooling for both sapphire and SiC devices. HEMTs on sapphire and SiC were tested from 25 to 500 °C; drain current and transconductance declined with temperature, with similar degradation ratios above 300 °C, while SiC devices maintained superior dc performance after thermal stress up to 500 °C, though both substrates performed similarly above 300 °C.

Abstract

The high-electron-mobility transistors (HEMTs) have been demonstrated on both sapphire and semi-insulating (SI) SiC substrates, and the dc characteristics of the fabricated devices were examined at temperatures ranging from 25 to 500 °C. The decrease in drain current and the transconductance with the increase of temperature have been observed. The decrease ratio of transconductance and drain current was similar for both the HEMTs on sapphire and SI–SiC substrates at and above 300 °C. The HEMTs on SiC substrates showed better dc characteristics after being subjected to thermal stress up to 500 °C. Although the SiC-based HEMTs showed better characteristics up to the temperature of 300 °C, compared with the sapphire-based HEMTs, similar dc characteristics were observed on both at and above 300 °C. For high-temperature applications (⩾300 °C), additional cooling arrangements are essential for both devices.