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Title : Heterogeneous defect domains in single-crystalline hexagonal WS2
Author : Hye Yun Jeong, Youngjo Jin, Seok Joon Yun, Jiong Zhao, Jaeyoon Baik, Dong Hoon Keum, Hyun Seok Lee*, and Young Hee Lee*
Abstract : Although intricate defects are inevitably generated during the synthesis of transition metal dichalcogenides (TMdCs) by chemical vapor deposition (CVD), the related discussions are mostly limited to chalcogen vacancies.[1-3] Here, we report the prevailing role of metal vacancies determining macroscopic material properties using a single-crystalline monolayer 2H-WS2 grown by CVD. The hexagonal shape of the WS2 flake is segmented into alternating triangular domains without forming explicit defective grain boundaries: sulfur-vacancy (SV)-rich and tungsten-vacancy (WV)-rich domains. The WV-rich domain with deep-trap states[4-6] revealed an electron-dedoping effect, and its electron mobility and photoluminescence were lower by one order of magnitude than those of the SV-rich domain with shallow-donor states.[7] The vacancy-induced strain and doping effects in such domains were investigated by analyzing spectral changes via Raman spectroscopy and the core-level shift via scanning photoelectron microscopy. Our work sheds light on tailoring macroscopic physical properties of two-dimensional materials via native defect engineering.