Synthesizing 1T-1H Two-Phase Mo1-xWxS2 Monolayers by Chemical Vapor Deposition.
Synthesizing 1T-1H Two-Phase Mo1-xWxS2 Monolayers by Chemical Vapor Deposition.
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DOI：
10.1021/acsnano.7b08149
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发表时间：
2018-01
期刊：
影响因子：
17.1
通讯作者：
Ziqian Wang;Yuhao Shen;Yoshikazu Ito;Yongzheng Zhang;Jing Du;T. Fujita;A. Hirata;Zheng Tang
中科院分区：
文献类型：
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作者：
Ziqian Wang;Yuhao Shen;Yoshikazu Ito;Yongzheng Zhang;Jing Du;T. Fujita;A. Hirata;Zheng Tang
二维过渡金属二硫属化物（transition-metaldichalcogenides，TMD）中的1 T-1H金属-半导体界面在利用TMD的带隙应用于电子器件方面起着至关重要的作用。虽然在剥离的2D纳米片和化学或物理处理的TMD中观察到1 T-1H两相结构，但由于1 T相的亚稳态性质，原则上不能在通过化学气相沉积（CVD）生长的大规模TMD单层中实现，化学气相沉积（CVD）是用于电子器件应用的制造方法。在这项研究中，我们报告的1 T-1H两相TMD单分子膜的CVD生长通过控制热应变和合金成分。结果发现，在平面内的热应变所产生的TMD单层和衬底之间的热膨胀系数的差异可以驱动1H到1 T的转变在CVD生长后的冷却过程中。此外，在2D晶体中的晶界作为1 T相的形核位点，并且来自合金化的晶格应变扰动显著地促进亚稳1 T相的形成。这项工作具有重要的意义，在裁剪结构和性能的CVD生长的二维TMD相工程。
1T-1H metal-semiconductor interfaces in two-dimensional (2D) transition-metal dichalcogenides (TMDs) play a crucial role in utilizing the band gaps of TMDs for applications in electronic devices. Although the 1T-1H two-phase structure has been observed in exfoliated 2D nanosheets and chemically or physically treated TMDs, it cannot in principle be achieved in large-scale TMD monolayers grown by chemical vapor deposition (CVD), which is a fabrication method for electronic device applications, because of the metastable nature of the 1T phase. In this study we report CVD growth of 1T-1H two phase TMD monolayers by controlling thermal strains and alloy compositions. It was found that in-plane thermal strains arising from the difference in thermal expansion coefficients between TMD monolayers and substrates can drive the 1H to 1T transition during cooling after CVD growth. Moreover, grain boundaries in the 2D crystals act as the nucleation sites of the 1T phase and the lattice strain perturbations from alloying noticeably promote the formation of the metastable 1T phase. This work has an important implication in tailoring structure and properties of CVD grown 2D TMDs by phase engineering.