Inlaid ReS2 Quantum Dots in Monolayer MoS2

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) are prospective materials for quantum devices owing to their inherent 2D confinements. They also provide a platform to realize even lower-dimensional in-plane electron confinement, for example, 0D quantum dots, for exotic physical properties. However, fabrication of such laterally confined monolayer (1L) nanostructure in 1L crystals remains challenging. Here we report the realization of 1L ReS₂ quantum dots epitaxially inlaid in 1L MoS₂ by a two-step chemical vapor deposition method combining with plasma treatment. The lateral lattice mismatch between ReS₂ and MoS₂ leads to size-dependent crystal structure evolution and in-plane straining of the 1L ReS₂ quantum dots. Optical spectroscopies reveal the abnormal charge transfer between the 1L ReS₂ quantum dots and the MoS₂ matrix, resulting from electron trapping in the 1L ReS₂ quantum dots. This study may shed light on the development of in-plane quantum-confined devices in 2D materials for potential applications in quantum information.