Rapid Wafer-Scale Growth of MoS_{2(1–<i>x</i>)}Se_2<i>x</i> Alloy Monolayers with Tunable Compositions and Optical Properties for High-Performance Photodetectors

Abstract

Monolayer transition metal dichalcogenide (TMD) alloys with tunable band gaps exhibit huge potential in nanoelectronics, optoelectronics, and photonics. The scalable production of uniform atomically thin TMD alloys is a key step for the realization of their device applications but remains a large challenge so far. Here, we report oxygen-assisted chemical vapor deposition (CVD) of uniform atomically thin MoS2(1–x)Se2x semiconductor alloys via a vertical Mo-precursor supply strategy. The growth scheme leads to the formation of highly crystalline MoS2(1–x)Se2x monolayer films within a short growth time of 8 min, which benefits from a stable and homogeneous Mo-precursor feeding environment and the synergic effect of NaBr and oxygen carrier on the growth. The high-resolution spectral characterizations and density functional theory calculations demonstrate that the chemical composition of the as-grown MoS2(1–x)Se2x monolayers can be continuously tuned from x = 0 to 1, leading to the corresponding band gap being gradually changed from 1.81 to 1.55 eV. This work provides an efficient strategy to obtain large-area uniform MoS2(1–x)Se2x monolayer alloys with tunable compositions and optical properties, which is essential for driving their applications in various functional optoelectronic devices, especially for high-performance flexible photodetectors.