The synthesis and tunable optical properties of two-dimensional alloyed Mo1-x W x S2 monolayer with in-plane composition modulations (0≤x≤1)

Bandgap engineering of two-dimensional layered transition metal dichalcogenides is a crucial strategy to realize the applications in nano/optoelectronics. In this research, we report the synthesis of single-phase alloyed Mo_1-xW_xS₂ (0 ≤ x ≤ 1) triangles in large scale using magnetron sputtering and chemical vapor deposition methods. Morphology and property characterizations have demonstrated that the alloyed Mo_1-xW_xS₂ flake is triangle and monolayer, and exhibits continuously tunable light emission from 677 nm (core) to 633 nm (edge), indicating the gradual evolution from pure MoS₂, alloyed Mo_1-xW_xS₂ to pure WS₂ across the lateral heterostructure. The growth mechanism of alloyed Mo_1-xW_xS₂ monolayer in the full composition range is discussed on the basis of time-dependent Mo/W vapor pressure. This ternary alloy with graded composition may possess fascinating functions in multi-band photodetection/light emission.