Low-temperature characteristics and gate leakage mechanisms of LPCVD-SiNx/AlGaN/GaN MIS-HEMTs

In this paper, we systematically investigated the static properties and gate current mechanism of low-pressure chemical vapor deposition-SiNx/AlGaN/GaN metal-insulator-semiconductor-high-electronmobility-transistor (MIS-HEMTs) at cryogenic temperature range from 10 K to 300 K. It is found that the threshold voltage of the device shows a positive shift due to the decreased carrier concentration at low temperature, and both the maximum transconductance and ON-resistance are improved at the low temperatures because of the enhanced electron mobility. Under very low electric field, the gate leakage exhibits ohmic conduction. With increasing forward gate bias, the dominant gate leakage mechanism at temperature below150 K gradually transits into trap-assisted tunneling, participating with a deep trap energy level of 0.73 eV in the SiNx dielectric, to Fowler-Nordheim (FN) tunneling. In contrast, the dominant gate leakage mechanism at temperature above 150 K transits from Poole-Frenkel emission, showing a low trap barrier height of 56 meV in the SiNx dielectric, to Fowler-FN tunneling with increasing forward gate bias. Under high reverse gate bias, carrier-limited gate current becomes the dominated gate leakage mechanism.

Automated summary

This paper systematically investigates the static properties and gate current mechanism of low-pressure chemical vapor deposition-SiNx/AlGaN/GaN metal-insulator-semiconductor-high-electron-mobility-transistor (MIS-HEMTs) at cryogenic temperature. The experiments show that the threshold voltage of the device shifts positively at low temperature, and both the maximum transconductance and ON-resistance are improved. The gate leakage mechanism transitions with increasing forward gate bias, from trap-assisted tunneling to Fowler-Nordheim tunneling at temperature below 150 K, and from Poole-Frenkel emission to Fowler-FN tunneling at temperature above 150 K.