Abstract
Atomically thin tungsten disulfide (WS2), a structural analogue to MoS2, has attracted great interest due to its indirect-to-direct band-gap tunability, giant spin splitting, and valley-related physics. However, the batch production of layered WS2 is underdeveloped (as compared with that of MoS2) for exploring these fundamental issues and developing its applications. Here, using a low-pressure chemical vapor deposition method, we demonstrate that high-crystalline mono- and few-layer WS2 flakes and even complete layers can be synthesized on sapphire with the domain size exceeding 50 × 50 μm(2). Intriguingly, we show that, with adding minor H2 carrier gas, the shape of monolayer WS2 flakes can be tailored from jagged to straight edge triangles and still single crystalline. Meanwhile, some intersecting triangle shape flakes are concomitantly evolved from more than one nucleus to show a polycrystalline nature. It is interesting to see that, only through a mild sample oxidation process, the grain boundaries are easily recognizable by scanning electron microscopy due to its altered contrasts. Hereby, controlling the initial nucleation state is crucial for synthesizing large-scale single-crystalline flakes. We believe that this work would benefit the controlled growth of high-quality transition metal dichalcogenide, as well as in their future applications in nanoelectronics, optoelectronics, and solar energy conversions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.