Dislocation-free two-dimensional concentric lateral heterostructures: MoS2-TaS2/Au(111)

We prepared two-dimensional concentric lateral heterostructures of the monolayer transition metal dichalcogenides MoS2 and TaS2 by reactive molecular beam epitaxy on chemically inert and weakly interacting Au(111). The heterostructures are in a size regime where quantum confinement can be expected. Despite large lattice mismatch a seamless interconnection of the two materials has been achieved, confirming that the semiconducting core is fully enclosed by a metallic border around its circumference. The resulting strain is analyzed on the atomic scale using scanning tunneling microscopy, corroborated by calculations based on empirical potentials and compared to results from finite elements simulations.