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

Abstract

In this paper, we systematically investigated the static properties and gate current mechanism of LPCVD-SiNx/AlGaN/GaN 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 increased intrinsic 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.

Special issue on wide-bandgap semiconductors and applications

“…They are essentially suitable for various applications targeting low losses and high operating frequencies and temperatures. This special issue evaluates a series of GaN-and AlGaN-based electronic devices proposed by Chinese researchers, such as Schottky barrier diodes (SBDs) [19], metal-oxide-semiconductor field effect transistors (MOSFETs) [20], high electron mobility transistors (HEMTs) [21][22][23][24][25], and so forth.…”

“…By adopting a p-NiO x gate cap layer and an ultra-thin AlGaN barrier layer, Du et al [21] proposed an etching-free fabrication method for a normally-off GaN HEMT design. Guo et al [22] investigated the static properties and gate current mechanism of SiN x /AlGaN/GaN metal-insulator-semiconductor HEMTs using low-pressure chemical vapor deposition. They found that, at low temperatures, the device's threshold voltage shifts positively, and both maximum transconductance and ON-resistance significantly improve.…”