Role of rough substrate on the growth of large single-crystal MoS2 by chemical vapor deposition
Role of rough substrate on the growth of large single-crystal MoS2 by chemical vapor deposition
复制标题
粗糙衬底对化学气相沉积大单晶MoS2生长的影响
DOI：
10.1016/j.apsusc.2019.01.211
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发表时间：
2019-05-15
影响因子：
6.7
通讯作者：
Zhang, Shengli
中科院分区：
文献类型：
--
作者：
Cheng, Zhaofang;Xia, Minggang;Zhang, Shengli
二维过渡金属二卤代化合物具有优异的电学和光学性质，在光电子器件中具有潜在的应用前景。这些优异的性能得益于大的单晶。在这里，我们证明了用化学气相沉积(CVD)方法可以在粗糙的SiO_2/Si衬底上制备出大尺寸的单晶单分子膜MoS_2。粗糙的SiO_2/Si衬底有两个优点。第一个问题是低成核密度。具有“山谷型”结构的粗糙衬底能有效地抑制形核密度。较低的形核密度似乎是由反应物表面浓度降低引起的，这一点已通过求解扩散方程得到了验证。另一个重要优势是较高的增长率。我们发现，自支撑MoS_2薄膜成功地生长在粗糙表面的“谷区”上。由于在悬浮生长过程中引入了温度梯度，计算得到的自支撑MoS2的生长速率是抛光表面的3倍。我们的发现为在粗糙表面上CVD生长MoS_2的机理提供了新的见解，并有望加速直接悬浮生长二维材料的发展，用于进一步的器件应用。
Two-dimensional transition metal dichalcogenides show a potential application in photoelectronic devices due to their excellent electronic and optical properties. These excellent properties benefit from large single crystals. Here, we demonstrate that large single crystal monolayer MoS2 can be synthesized on rough SiO2/Si substrate via chemical vapor deposition (CVD) method. Rough SiO2/Si substrate has two advantages. The first one is low nucleation density. The rough substrate with "hill and valley" structures can effectively suppress nucleation density. The lower nucleation density seems to be caused by the reduced surface concentrations of reactants, which has been verified by solving the diffusion equation. Another important advantage is the higher growth rate. We found that the free-standing MoS2 films were successfully grown over the "valley" regions of the rough surface. The calculated growth rate of free-standing MoS2 is three times as that on polished surface, which comes from the introduction of temperature gradient during suspended growth. Our findings have provided new insights into the mechanisms underlying CVD MoS2 growth on rough surfaces and are expected to accelerate the development of directly suspended growth of two-dimensional material for further device applications.