Abstract
AbstractTungsten diselenide (WSe2) possesses extraordinary electronic properties for applications in electronics, optoelectronics, and emerging exciton physics. The synthesis of monolayer WSe2 film is of topmost for device arrays and integrated circuits. The monolayer WSe2 film has yet been reported by thermal chemical vapor deposition (CVD) approach, and the nucleation mechanism remains unclear. Here, we report a pre‐seeding strategy for finely regulating the nuclei density at an early stage and achieving a fully covered film after chemical vapor deposition growth. The underlying mechanism is heterogeneous nucleation from the pre‐seeding tungsten oxide nanoparticles. At first, we optimized the precursor concentration for pre‐seeding. Besides, we confirmed the superiority of the pre‐seeding method, compared with three types of substrate pretreatments, including nontreatment, sonication in an organic solvent, and oxygen plasma. Eventually, the high‐quality synthetic WSe2 monolayer film exhibits excellent device performance in field‐effect transistors and photodetectors. We extracted thermodynamic activation energy from the nucleation and growth data. Our results may shed light on the wafer‐scale production of homogeneous monolayer films of WSe2, other 2D materials, and their van der Waals heterostructures.image
Highlights
transition metal dichalcogenides (TMDCs) become important for semiconductor physics and energy conversion devices because of their high electron mobility,[14] energy density, and electrochemical activity.[15]
The data demonstrate the full film of monolayer WSe2 forms over the pre-seeding treated substrate
This approach has the advantage of short growth duration compared with other full film chemical vapor deposition (CVD) synthesis works (30–40 min).[46,55]
Summary
The advances of graphene[1,2] have aroused great attention to a variety of novel two-dimensional (2D) functional materials with unique physical and chemical properties such as graphite-like carbon nitride,[3] transition metal carbon/nitride (MXene),[4] transition metal dichalcogenides (TMDCs),[5,6,7] black phosphorus,[8] hexagonal boron nitride,[9] metal–organic frameworks,[10] covalent organic frameworks,[11] inorganic perovskite,[12] and organic–inorganic hybrid perovskite.[13]. TMDCs become important for semiconductor physics and energy conversion devices because of their high electron mobility,[14] energy density, and electrochemical activity.[15] Most TMDCs are n-type conducting.[16,17] One needs a p-type material for fabricating a p-n junction, which is a fundamental structure for optoelectronics. The tungsten diselenide (WSe2) is one of the few choices for p-type charge transport, which enables it to be a vital 2D semiconducting material. The stacking between WSe2 and other TMDCs broadens the van der Waals heterostructures for electronic and optoelectronic device applications.[21]
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