Large-scale synthesis of atomically thin ultrawide bandgap beta-Ga2O3 using a liquid gallium squeezing technique

Abstract

beta-Ga2O3, an emerging ultrawide bandgap (UWBG) semiconductor, offers promising properties for next-generation power electronics, chemical sensors, and solar-blind optoelectronics. Scaling down of beta-Ga2O3 to the atomic level affords the advantages of two-dimensional (2D) materials, while maintaining the inherent properties of the parent bulk counterpart. Here, we demonstrate a simple approach to synthesize ultrathin millimeter-size beta-Ga2O3 sheets using a liquid gallium squeezing technique. The GaOx nanolayer produced by stamping liquid gallium under the Cabrera-Mott oxidation was converted into few-atom-thick beta-Ga2O3 via thermal annealing under atmospheric conditions. This approach was also applied to various substrates such as SiO2, Si, graphene, quartz, and sapphire to heteroepitaxially synthesize 2D beta-Ga2O3 on a target substrate. Finally, we propose a patterning strategy combining the squeezing technique with conventional lithography to obtain a beta-Ga2O3 layer with a controllable thickness and shape. Our synthetic method has the potential to overcome the limitations of conventional beta-Ga2O3 growth methods, paving a path for applications in UWBG-based (opto-)electronics with a high throughput in a cost-effective manner.