期刊
ACS NANO
卷 9, 期 5, 页码 5189-5197出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.5b00554
关键词
transition-metal dichalcogenide; vacancy; defect dynamics; inversion domain; grain boundaries
类别
资金
- U.S. DOE [DE-FG02-09ER46554]
- U.S. Department of Energy, Office of Science, Basic Energy Science, Materials Sciences and Engineering Division
- ORNL's Center for Nanophase Materials Sciences (CNMS) - Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. DOE
- Office of Science of the US Department of Energy [DE-AC02-05CH11231]
Sixty degree grain boundaries in semiconducting transition-metal dichalcogenide (TMDC) monolayers have been shown to act as conductive channels that have profound influence on both the transport properties and exciton behavior of the monolayers. Here, we show that annealing TMDC monolayers at high temperature induces the formation of large-scale inversion domains surrounded by such 60 degrees grain boundaries. To study the formation mechanism of such inversion domains, we use the electron beam in a scanning transmission electron microscope to activate the dynamic process within pristine TMDC monolayers. The electron beam acts to generate chalcogen vacancies in TMDC monolayers and provide energy for them to undergo structural evolution. We directly visualize the nucleation and growth of such inversion domains and their 60 degrees grain boundaries atom-by-atom within a MoSe2 monolayer and explore their formation mechanism. Combined with density functional theory, we conclude that the nucleation of the inversion domains and migration of their 60 degrees grain boundaries are driven by the collective evolution of Se vacancies and subsequent displacement of Mo atoms, where such a dynamical process reduces the vacancy-induced lattice shrinkage and stabilizes the system. These results can help to understand the performance of such materials under severe conditions (e.g., high temperature).
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