Direct and Indirect Interlayer Excitons in a van der Waals Heterostructure of hBN/WS2/MoS2/hBN
Direct and Indirect Interlayer Excitons in a van der Waals Heterostructure of hBN/WS2/MoS2/hBN
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DOI：
10.1021/acsnano.7b08253
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发表时间：
2018-03-01
期刊：
影响因子：
17.1
通讯作者：
Kitaura, Ryo
中科院分区：
文献类型：
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作者：
Okada, Mitsuhiro;Kutana, Alex;Kitaura, Ryo
由多通道系统组成的货车德瓦耳斯（vdW）异质结构可以显示来自电子结构中的几个谷的层间激子的激子光学响应。在这项工作中，我们研究了沉积在六方氮化硼（hBN）薄片上的vdW异质结构WS 2/MoS 2的光致发光（PL）。在室温下观察到的来自所制造的异质结构的PL光谱显示在1.3-1.7 eV处的PL峰，这在单独的WS 2或MoS 2单层的PL光谱中不存在。我们观察到的低能量PL峰可以分解成三个不同的峰。通过详细的光致发光测量和理论分析，包括光致发光成像、时间分辨光致发光测量，以及用G（0）W（0）求解Bethe-Salpeter方程计算介电函数Ω（ω），我们得出这三个光致发光峰来源于直接的K-K层间激子、间接的Q-Gamma层间激子和间接的K-Gamma层间激子。
A van der Waals (vdW) heterostructure composed of multivalley systems can show excitonic optical responses from interlayer excitons that originate from several valleys in the electronic structure. In this work, we studied photoluminescence (PL) from a vdW heterostructure, WS2/MoS2, deposited on hexagonal boron nitride (hBN) flakes. PL spectra from the fabricated heterostructures observed at room temperature show PL peaks at 1.3-1.7 eV, which are absent in the PL spectra of WS2 or MoS2 monolayers alone. The low-energy PL peaks we observed can be decomposed into three distinct peaks. Through detailed PL measurements and theoretical analysis, including PL imaging, time-resolved PL measurements, and calculation of dielectric function epsilon(omega) by solving the Bethe-Salpeter equation with G(0)W(0), we concluded that the three PL peaks originate from direct K-K interlayer excitons, indirect Q-Gamma interlayer excitons, and indirect K-Gamma interlayer excitons.