Dual laser beam-assisted chemical doping of 2D layered material

The unique optoelectronic properties of two-dimensional (2D) layered materials typically manifest in ultrathin few-layer or monolayer formats. Such atomically thin and delicate structures present challenges to processing with conventional fabrication methods. Here, we introduce a highly tunable doping method in atomically thin Transition Metal Dichalcogenide (TMDC) by dual laser beam assisted chlorine doping process. Two laser beams with selected photon energies and geometric configuration separately manage defect generation through direct laser heating and chlorine radical supply via a parallelly coupled Ultraviolet (UV) pulsed laser beam. This process can provide a synergistic p-type doping effect in molybdenum disulfide (MoS₂, a representative TMDC), owing to a higher charge transfer rate of chlorine element to MoS₂ when anchored at sulfur (S) vacancy compared to when it binds at pristine MoS₂ surface. The quenching of negative trions (X-: e-e-h) and resultant dominance of excitons (X: e-h) by hole doping effect significantly boosts photoluminescence (PL) intensity. Moreover, the strong binding of chlorine at S-vacancy sustains the enhanced PL intensity over a few months. This result provides a promising route to facile construction of robust and stable atomically thin photonic devices.