Grain boundaries with 60¡ tilt-angle in semiconducting transition-metal dichalcogenide (TMDC) monolayers display metallic behavior and can drastically quench local photoluminescence. Fundamental understanding of the atomic mechanism for the formation and dynamics of the inversion domains and 60¡ grain boundaries provides the keys to tuning the electronic and optical properties of monolayer TMDC materials via defect engineering. Electron microscopy and density functional theory revealed that the segregation of Se vacancies induced atomic displacement that led to the nucleation and growth of inversion domains and 60¡ grain boundaries. The researchers also demonstrated large-scale creation of inversion domains by high-temperature annealing, in which thermal energy activated similar defect evolution.
J. Lin, S. T. Pantelides, and W. Zhou, “Vacancy-Induced Formation and Growth of Inversion Domains in Transition-Metal Dichalcogenide Monolayer,” ACS Nano (2015). DOI: 10.1021/acsnano.5b00554
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