Unraveling the Defect Emission and Exciton–Lattice Interaction in Bilayer WS2
Unraveling the Defect Emission and Exciton–Lattice Interaction in Bilayer WS2
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揭示双层 WS2 中的缺陷发射和激子与晶格相互作用
DOI：
10.1021/acs.jpcc.8b11011
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Jun Zhang
中科院分区：
文献类型：
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作者：
Qing-Hai Tan;Shu-Liang Ren;Tao Shen;Xue-Lu Liu;Wei Shi;Yu-Jia Sun;Hui-Xiong Deng;Ping-Heng Tan;Jun Zhang
二维半导体的缺陷态和激子在基础研究和器件应用中发挥着重要作用。在这里，我们报道了双层 WS2 的缺陷发射和激子-晶格相互作用。这些缺陷发射表现出非常窄的线宽、双峰、空间局域化、泵浦功率饱和，并且可以在高达 180 K 的温度下生存。这些缺陷发射的行为意味着它应该是作为单光子源的良好候选者。除了缺陷发射之外，还确定了由于带间跃迁导致的直接激子和两个间接激子。通过分析激子的温度依赖性光致发光（PL）光谱，我们获得了所有激子的德拜温度、激子-声子耦合常数和压力系数项。结合PL实验和密度泛函理论计算，我们将两个间接激子分别归因于Λ-K和Λ-Γ跃迁。我们的研究不仅可以更好地理解多层材料中的缺陷发射和能带结构，而且还为二维层状系统中的缺陷和能带工程提供了机会。
Defect states and exciton of two-dimensional semiconductors play an important role in fundamental research and device applications. Here, we reported the defect emissions and exciton–lattice interaction of bilayer WS2. These defect emissions show a very narrow linewidth, doublet peaks, spatial localization, saturation with pumping power and can survive up to 180 K. The behavior of these defect emissions means it should be a good candidate as a single photon source. Besides defect emissions, direct exciton and two indirect excitons due to band-to-band transition are identified. By analyzing the temperature-dependent photoluminescence (PL) spectra of excitons, we obtained the Debye temperature, exciton–phonon coupling constant, and pressure coefficient terms of all excitons. Combining the PL experiments and density functional theory calculations, we attributed two indirect excitons to the Λ–Kand Λ–Γ transitions, respectively. Our study not only gives a better understanding of the defect emissions and energy band structure in multilayer materials, but also provides an opportunity for defect and band engineering in two-dimensional layered systems.