Seed‐mediated self‐driven nucleation growth of doped monolayer <scp> WS ₂ </scp> film

Abstract The substitutional doping of two‐dimensional (2D) transition metal dichalcogenides (TMDs) is essential for tuning their electronic and optoelectronic properties. However, conventional doping methods often suffer from the edge enrichment by dopant atoms, particularly for rare‐earth dopants with large ionic radii, owing to their tendency to migrate toward high‐energy edge sites during growth. Herein, we present a seed‐mediated, self‐driven nucleation strategy that leverages the high surface energy of stepped sapphire substrates to pre‐adsorb dopant atoms at the step edges. These sites guide the localized nucleation and incorporation of the dopants, thereby effectively suppressing edge segregation. Using this approach, we synthesized centimeter‐scale monolayer Yb‐doped WS 2 films with incorporated substitutional atoms, along with other metal‐doped WS 2 films. The introduction of mid‐gap states near the conduction band in monolayer Yb‐doped WS 2 films was further demonstrated by the characterization of the bound exciton emission and electronic density of states. This study broadens the pathways for the controllable synthesis of substitutional 2D materials and extends the potential for developing novel 2D optoelectronic devices. image