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

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.