Deciphering the structure-photoluminescence correlation at small-tilt-angle grain boundaries in monolayer WS2
Deciphering the structure-photoluminescence correlation at small-tilt-angle grain boundaries in monolayer WS2
复制标题
破译单层 WS2 小倾斜角晶界处的结构-光致发光相关性
DOI：
10.1063/5.0097638
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发表时间：
2022-08-01
影响因子：
4
通讯作者：
Lin, Junhao
中科院分区：
文献类型：
--
作者：
Hou, Fuchen;Zhang, Yubo;Lin, Junhao
CVD法生长的大尺寸过渡金属二硫属化合物单层薄膜中经常会出现晶界，这会影响材料的电学和光学性能。光致发光（PL）可以很容易地在GB处猝灭/增强，然而，在先前的研究中，仅在相对大的倾斜角（θ> 14）下进行研究。在这里，我们实验研究的PL性能的单层WS 2 GB的倾斜角小到几度。相反，传统的智慧，我们发现PL强度保持不变的GB时，他们的倾斜角θ≤ 8度。通过对位错核的详细结构分析，阐明了异常的PL行为。当倾角较小时，缺陷芯引入的应变场分布稀疏，没有相互耦合，并且沿着晶界的化学计量比保持得很好。这两个关键的结构特征的小倾斜角GB允许激子扩散透明的GB，导致光学和电子性质的影响可以忽略不计，我们的第一原理模拟验证。小倾角发光带的光致发光不变量为CVD生长的圆片级技术及其光学应用的未来发展提供了启示。由AIP Publishing独家授权出版。
Grain boundaries (GBs) frequently emerge in a CVD-grown large-scale transition metal dichalcogenides monolayer thin film, which affect the electronic and optical properties of the material. Photoluminescence (PL) can be easily quenched/enhanced at GBs, which are, however, merely investigated in relatively large tilt angles ( theta > 14 ) in previous research. Here, we experimentally examine the PL properties of monolayer WS2 GBs with tilt angles as small as a few degrees. Contrary to conventional wisdom, we find that PL intensity remains intact by the GBs when their tilt angles theta & LE; 8 & DEG;. The abnormal PL behavior is elucidated by a detailed structure analysis on the dislocation cores. For a small tilt angle, the strain fields introduced by the defective cores are sparsely distributed without mutual coupling, and the chemical stoichiometry along the GBs preserves very well. These two key structural features of the small-tilt-angle GBs allow excitons to diffuse transparently across the GB, leading to a neglectable influence on the optical and electronic properties, as verified by our first-principle simulations. The PL invariant of the small-tilt-angle GBs sheds light on the future development of CVD-grown wafer-scale techniques and their optical applications. Published under an exclusive license by AIP Publishing.