Tellurization Velocity-Dependent Metallic-Semiconducting Metallic Phase Evolution in Chemical Vapor Deposition Growth of Large Area, Few-Layer MoTe2
Tellurization Velocity-Dependent Metallic-Semiconducting Metallic Phase Evolution in Chemical Vapor Deposition Growth of Large Area, Few-Layer MoTe2
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大面积、少层 MoTe2 化学气相沉积生长中与碲化速度相关的金属-半导体金属相演化
DOI：
10.1021/acsnano.6b08109
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发表时间：
2017
期刊：
影响因子：
17.1
通讯作者：
Chang Haixin
中科院分区：
文献类型：
--
作者：
Yang Li;Zhang Wenfeng;Li Jie;Cheng Shuai;Xie Zijian;Chang Haixin
MoTe2等二维过渡金属二卤化物(TMD)的相工程在各种器件应用中提供了巨大的机会。然而，到目前为止，已有的方法大多只针对MoTe2薄膜的小区域局部相变或通过激光照射、机械应变或引导型生长的某些相的生长。在大面积、少层的MoTe2的直接生长中，获得简单、可调、可逆和连续的不同相之间的相变和演化仍然是具有挑战性的。在这里，我们开发了一种简单的方法来实现相控制和相变，并报道了在化学气相沉积(CVD)大面积、少层MoTe2生长中高度可调的、与电化速度相关的金属-半导体-金属相的演变。我们发现，根据所采用的电化速度，将出现四个不同的阶段，包括2H和1T‘两种不同类型的共存相、100%的2H相和100%的1T’相。重要的是，要获得100%的2H相MoTe2，而100%的1T‘相需要较快的电化速度，则应严格控制电化速度。我们进一步发现，这种金属-半导体-金属相演化具有均匀的空间分布，不同于以往的报道，在相变过程中通常会发现明显的相分离。由此得到的MoTe2显示出高质量，具有可与机械剥离材料相媲美的室温流动性。这一结果可能会影响TMDs和其他用于Weyl半金属拓扑物理的2D材料的大规模相工程，以及潜在的2D半导体器件应用。
Phase engineering of two-dimensional (2D) transition metal dichalcogenides (TMDs) such as MoTe2offers 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 MoTe2film 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 MoTe2still 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 MoTe2shows 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.