Quantum coupling and self-heating impacts on threshold voltages of GaN metal–insulator-semiconductor high-electron-mobility transistors

Abstract

A transient heat conduction equation has been proposed to describe the cooling process of a hot two-dimensional electron gas layer in a GaN-based transistor. This equation serves as the basis for a physical analytical model that explains the impacts of hot electrons in the hot two-dimensional electron gas layer via quantum coupling on the threshold voltage of GaN-based transistors. The temperature of the two-dimensional electron gas layer decreases to ambient temperature as time increases, and the threshold voltage shifts caused by such a temperature will recover with time. The proposed model accurately reflects the observed recovery of threshold voltage over time in experiments. At the same time, it offers insight into how the gate voltage, the source-drain voltage, and the ambient temperature can shift the threshold voltage in these transistors. The simplicity and analytic nature of this proposed model not only provide a physical origin of the threshold voltage instability in GaN-based devices but also offer the possibility for improving device reliability by selecting appropriate device physical parameters.