Gallium-Nitride Field Effect Transistors in Extreme Temperature Conditions

Compact power electronic circuits and higher operating temperatures of switching devices call for an analysis and verification on the impact of the parasitic components in these devices. The found drift mechanisms in a gallium-nitride field effect transistors (GaN-FET) are studied by literature and related to measurement results. The measurements in extreme temperature conditions are far beyond the manufacturer-recommended operating range. Influences to parasitic elements in both static and dynamic operation of the GaN-FETs are investigated and related toward device losses in switch-mode power electronic circuits with the example of a half-bridge circuit. In this article, static operation investigation on the effect of temperature toward resistance, leakage currents, and reverse conduction is conducted. Dynamic operation between the two states of GaN-FET is also addressed and related to the potential impact in a switching circuit losses. A thermal chamber was built to precisely measure the effect of temperature toward parasitic elements in the devices using a curve tracer. It was found that the increment in RDSon, IDSS, IGSS, and VSD can be justified by the literature and verified by measurements. Incremental COSS and decreasing VGSth was found when exposing devices to extreme temperatures. These two parameters give real challenge over designing circuits at high temperature where timing is critical. Albeit temperature challenges, it is found that investigated GaN-FETs have potential to be used in extreme temperature-operating conditions.