Controlled Fabrication of Native Ultra-Thin Amorphous Gallium Oxide from 2D Gallium Sulfide for Emerging Electronic Applications

TL;DR

This paper demonstrates a controlled oxidation process of 2D gallium sulfide to create ultrathin gallium oxide layers, enabling low-power resistive memory devices with high endurance and retention.

Contribution

It introduces a novel oxygen plasma oxidation method to produce ultrathin GaS$_x$O$_y$ layers on 2D GaS, facilitating low-power electronic memory applications.

Findings

Achieved ~4 nm native gallium oxide on 2D GaS

Demonstrated resistive switching with low energy per operation

Maintained endurance of 350 cycles and retention of 10^4 seconds

Abstract

Oxidation of two-dimensional (2D) layered materials has proven advantageous in creating oxide/2D material heterostructures, opening the door for a new paradigm of low-power electronic devices. Gallium (II) sulfide ($\beta$-GaS), a hexagonal phase group III monochalcogenide, is a wide bandgap semiconductor with a bandgap exceeding 3 eV in single and few layer form. Its oxide, gallium oxide (Ga$_2$O$_3$), combines large bandgap (4.4-5.3 eV) with high dielectric constant (~10). Despite the technological potential of both materials, controlled oxidation of atomically-thin $\beta$-GaS remains under-explored. This study focuses into the controlled oxidation of $\beta$-GaS using oxygen plasma treatment, achieving ultrathin native oxide (GaS$_x$O$_y$, ~4 nm) and GaS$_x$O$_y$/GaS heterostructures where the GaS layer beneath remains intact. By integrating such structures between metal electrodes and applying electric stresses as voltage ramps or pulses, we investigate their use for resistive random-access memory (ReRAM). The ultrathin nature of the produced oxide enables low operation power with energy use as low as 0.22 nJ per operation while maintaining endurance and retention of 350 cycles and 10$^4$ s, respectively. These results show the significant potential of the oxidation-based GaS$_x$O$_y$/GaS heterostructure for electronic applications and, in particular, low-power memory devices.