Investigation of Magnesium Silicate as an Effective Gate Dielectric for AlGaN/GaN Metal Oxide High Electron Mobility Transistors (MOSHEMT)

TL;DR

This paper explores magnesium silicate as a new gate dielectric material for AlGaN/GaN MOSHEMTs, demonstrating reduced leakage current and suitable dielectric properties through sputtering and annealing processes.

Contribution

It introduces magnesium silicate as an effective gate dielectric for AlGaN/GaN devices, with experimental validation of its electrical and physical properties.

Findings

Significant reduction in reverse leakage current by three orders of magnitude.

Successful deposition and annealing of stoichiometric Mg-Silicate confirmed by XPS.

Measured dielectric constant of Mg-Silicate approximately 6.6.

Abstract

In this study, a 6 nm layer of Magnesium Silicate (Mg-Silicate) was deposited on AlGaN/GaN heterostructure by sputtering of multiple stacks of MgO and SiO$_{2}$, followed by rapid thermal annealing in a nitrogen (N$_{2}$) environment. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometric Mg-Silicate (MgSiO$_{3}$) after being annealed at a temperature of 850 $^\circ$C for 70 seconds. Atomic force microscopy (AFM) was employed to measure the root mean square (RMS) roughness (2.20 nm) of the Mg-Silicate. A significant reduction in reverse leakage current, by a factor of three orders of magnitude, was noted for the Mg-Silicate/AlGaN/GaN metal-oxide-semiconductor (MOS) diode in comparison to the Schottky diode. The dielectric constant of Mg-Silicate($\mathcal{E}_{Mg-Silicate}$) and the interface density of states (D$_{it}$) with AlGaN were approximated at $\sim$ 6.6 and 2.0 $\times$ 10$^{13}$ cm$^{-2}$eV$^{-1}$ respectively, utilizing capacitance-voltage (CV) characteristics.