Journal
ACS NANO
Volume 11, Issue 2, Pages 1964-1972Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.6b08109
Keywords
phase engineering; two-dimensional materials; large-area synthesis; metallic-semiconducting-metallic phase transition
Categories
Funding
- National Natural Science Foundation of China [51502101, 51402118, 61674063]
- National Basic Research Program of China [2015CB258400]
- National Key Research and Development Program of China [2016YFB0700700]
- Fundamental Research Funds for the Central Universities in Huazhong University of Science and Technology [2015QN006]
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Phase engineering of two-dimensional (2D) transition metal dichalcogenides (TMDs) such as MoTe2 offers tremendous opportunities in various device applications. However, most of the existing methods so far only address the small -area local phase change or the growth of certain kinds of phases of MoTe2 film by laser irradiation, mechanical strain, or procursor type. Obtaining facile, tunable, reversible, and continuous -phase transition and evolution between different phases in direct growth of large area, few -layer MoTe2 still remains challenging. Here, we develop a facile method to achieve phase control and transition and report a highly tunable, tellurization velocity -dependent metallic semiconducting metallic phase evolution in chemical vapor deposition (CVD) growth of large -area, few layer MoTe2. We found four different phase stages, including two different types of coexistence phases of both 2H and 1 T ' phases, 100% 2H phase, and 100% 1T' phase, would emerge, relying on the adopted tellurization velocity. Importantly, the tellurization velocity should be extremely controlled to obtain 100% 2H phase MoTe2, while 100% 1T/ phase requires a fast tellurization velocity. We further found that such metallic semiconducting metallic phase evolution took place with a homogeneous spatial distribution and differs from previous reports in which obvious phase separations are usually found during the phase transition. The resulting MoTe2 shows high quality with room -temperature mobility comparable with mechanically exfoliated materials. The results might impact large-scale phase engineering of TMDs and other 2D materials for Weyl semimetal topological physics and potential 2D semiconductor device applications.
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