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Direct Visualization of Grain Boundaries in 2D Monolayer WS 2 via Induced Growth of CdS Nanoparticle Chains
Author(s) -
Lan Changyong,
Li Dapan,
Zhou Ziyao,
Yip SenPo,
Zhang Heng,
Shu Lei,
Wei Renjie,
Dong Ruoting,
Ho Johnny C.
Publication year - 2019
Publication title -
small methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.66
H-Index - 46
ISSN - 2366-9608
DOI - 10.1002/smtd.201800245
Subject(s) - grain boundary , materials science , monolayer , heterojunction , nanoparticle , nucleation , chemical vapor deposition , wafer , electron mobility , nanotechnology , optoelectronics , chemistry , microstructure , composite material , organic chemistry
To date, wafer‐scale synthesis of two‐dimensional (2D) materials are well achieved by chemical vapor deposition, but the obtained monolayers typically have multidomains with electrical and optoelectronic properties affected by grain boundaries and domain sizes. When these 2D materials are used as the growth templates, these boundaries would also provide unknown influences to the successive heterostructure formation for extended applications. Here, for the first time, direct visualization of grain boundaries in monolayer WS 2 film can be realized by the growth of CdS nanoparticles. Specifically, CdS is found to first preferentially nucleate and form as nanoparticle chains along WS 2 grain boundaries in a random manner, independent of the grain boundary characteristics. Due to electron scattering and type II band alignment at the WS 2 –CdS heterojunction, WS 2 reduces in its mobility while becoming enhanced in its electron concentration. Notably, the WS 2 –CdS heterostructure also yields improved carrier separation and collection for the photodetection performance enhancement. All these results can facilitate the detailed evaluation of crystalline grains‐related information of 2D materials and provide thorough understanding on the effect of these overgrown CdS on underlying WS 2 monolayers, being extremely important to further optimize and enable their functionalities for advanced device applications.