Kirkendall Voids in Monolayer Mo_xTa_yS₂ Alloys on Au(111)

During the growth of monolayer MoS₂-TaS₂ heterostructures, we observe the Kirkendall effect, a phenomenon not previously reported in systems with reduced dimensionality. The lateral heterostructures were prepared by reactive molecular beam epitaxy on chemically inert and weakly interacting Au(111). Enclosing MoS₂ islands in TaS₂ by exposing them to a sulfur-rich environment at elevated temperatures facilitates diffusion at the interface. The resulting heterostructures exhibit characteristic 2D Kirkendall voids surrounded by a Mo_xTa_yS₂ alloy region. These findings reveal defect-mediated processes in low-dimensional systems and open new avenues for designing 2D lateral heterostructures with intricate morphologies.