期刊
ACS NANO
卷 12, 期 2, 页码 2070-+出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b00398
关键词
2D materials; WSe2; phase transition; surface functionalization; potassium
类别
资金
- NSFC [21573156]
- National Key Basic Research Program of China [2015CB856505]
- Natural Science Foundation of Jiangsu Province [BK20170005]
- Singapore MOE [R143-000-652-112]
- National Science Foundation (NSF) CAREER [DMR-1455346]
- NSF [EFRI-2DARE-1542815]
- China Scholarship Council
- National Science Foundation [ACI-1548562]
- Directorate For Engineering [1542815] Funding Source: National Science Foundation
Structures determine properties of materials, and controllable phase transitions are, therefore, highly desirable for exploring exotic physics and fabricating devices. We report a direct observation of a controllable semiconductor-metal phase transition in bilayer tungsten diselenide (WSe2) with potassium (K) surface functionalization. Through the integration of in situ field-effect transistors, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy measurements, and first-principles calculations, we identify that the electron doping from K adatoms drives bilayer WSe2 from a 2H phase semiconductor to a IT' phase metal. The phase transition mechanism is satisfactorily explained by the electronic structures and energy alignment of the 2H and IT' phases. This explanation can be generally applied to understand doping-induced phase transitions in two-dimensional (2D) structures. Finally, the associated dramatic changes of electronic structures and electrical conductance make this controllable semiconductor-metal phase transition of interest for 2D semiconductor based electronic and optoelectronic devices.
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