Laser-assisted in situ fabrication of atomically thin Ga2O3 films for dielectric applications

Abstract

Two-dimensional (2D) gallium oxide (Ga₂O₃) has emerged as a high-κ dielectric material for optoelectronic applications due to its ultra-wide bandgap and large-scale productivity. However, the usage of thermal treatment during the liquid-metal-assisted fabrication process could degrade the quality of channel materials. Here, we report a laser-assisted in situ oxidation method combined with a confinement template-assisted squeeze technique to fabricate centimeter-scale 2D atomically thin Ga₂O₃ films from liquid gallium metal surfaces at room temperature. This approach avoids thermal damage to vulnerable materials. The laser-accelerated oxidation mechanism is elucidated as photocatalytic oxidation of initial Ga/Ga₂O_3−x surface through the integration of multi-wavelength laser radiation experiments and density functional theory calculations. We further demonstrate top-gated field-effect transistors (FETs) using black phosphorus (BP) and MoS₂ as channel materials, with thin-film Ga₂O₃ as the gate dielectrics. BP-based FETs show gate-tunable mid-infrared photoresponse with responsivity at the order of 0.1 A·W⁻¹ level. MoS₂-based FETs exhibit a photo-detectivity of 6.8 × 10¹² Jones in the visible-light spectrum, an on/off ratio over 10⁸, a subthreshold swing of 73.6 mV decade⁻¹, and gate leakage currents below 4 × 10⁻⁶ A cm⁻² at 8 MV cm⁻¹. This room-temperature laser-oxidation approach enables scalable integration of ultrathin oxide dielectrics with sensitive 2D materials for next-generation nanoelectronics.