Ultraviolet Light-Induced Functional Group Formation on Molybdenum Disulfide for Patterned Atomic Layer Deposition

Two-dimensional (2D) nanoelectronics using transition-metal dichalcogenide (TMD) channels, such as MoS2, promise smaller, faster, and more energy-efficient computing. A key challenge of TMD processing is the precise patterning of gate dielectrics. Here, we demonstrate patterned atomic layer deposition (ALD) on MoS2 using pretreatment methods comprising electron beam or ultraviolet (UV) irradiation in the presence of water vapor. The UV-based method dissociates water molecules and produces localized reactive species that bind to the 2D material surface and act as nucleation sites for ALD. UV light exposure facilitates exposure of large sample areas, and we demonstrate localized patterning using shadow masks to control exposure areas. Full functionalization occurs with 90 min of UV/H2O exposure with our equipment, resulting in dense ZnO films. Further, we find that the process is transferable to highly ordered pyrolytic graphite, opening additional material pathways toward 2D nanoelectronic devices.