In-situ dielectric Al2O3/\b{eta}-Ga2O3 Interfaces Grown Using Metal-organic Chemical Vapor Deposition

TL;DR

This paper demonstrates the in-situ growth of Al2O3 dielectric on β-Ga2O3 using MOCVD, showing promising interface quality and electrical properties for high-performance Ga2O3-based devices.

Contribution

It introduces a novel in-situ MOCVD process for Al2O3 on β-Ga2O3, providing an alternative to ALD with detailed interface and electrical characterization.

Findings

Average D_it of 7.8×10^11 cm^-2 eV^-1 at the interface

Conduction band offset of 1.7 eV consistent with literature

Breakdown field of approximately 5.8 MV/cm

Abstract

High-quality dielectric-semiconductor interfaces are critical for reliable high-performance transistors. We report the in-situ metalorganic chemical vapor deposition (MOCVD) of Al$_2$O$_3$ on $\beta$-Ga$_2$O$_3$ as a potentially better alternative to the most commonly used atomic layer deposition (ALD). The growth of Al$_2$O$_3$ is performed in the same reactor as Ga$_2$O$_3$ using trimethylaluminum and O$_2$ as precursors without breaking the vacuum at a growth temperature of 600 $^0$C. The fast and slow near interface traps at the Al$_2$O$_3$/ $\beta$-Ga$_2$O$_3$ interface are identified and quantified using stressed capacitance-voltage (CV) measurements on metal oxide semiconductor capacitor (MOSCAP) structures. The density of shallow and deep level initially filled traps (D$_{it}$) are measured using ultra-violet (UV) assisted CV technique. The average D$_{it}$ for the MOSCAP is determined to be 7.8 $\times$ 10$^{11}$ cm$^{-2}$eV$^{-1}$. The conduction band offset of the Al$_2$O$_3$/ Ga$_2$O$_3$ interface is also determined from CV measurements and found out to be 1.7 eV which is in close agreement with the existing literature reports of ALD Al$_2$O$_3$/ Ga$_2$O$_3$ interface. The current-voltage characteristics are also analyzed and the average breakdown field is extracted to be approximately 5.8 MV/cm. This in-situ Al$_2$O$_3$ dielectric on $\beta$-Ga$_2$O$_3$ with improved dielectric properties can enable Ga$_2$O$_3$-based high performance devices.