Experimental Evidence of Anisotropic and Stable Charged Excitons (Trions) in Atomically Thin 2D ReS2
Experimental Evidence of Anisotropic and Stable Charged Excitons (Trions) in Atomically Thin 2D ReS2
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DOI：
10.1002/adfm.201905961
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发表时间：
2019-10
影响因子：
19
通讯作者：
Xiaofan Wang;K. Shinokita;Y. Miyauchi;N. Cuong;S. Okada;K. Matsuda
中科院分区：
文献类型：
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作者：
Xiaofan Wang;K. Shinokita;Y. Miyauchi;N. Cuong;S. Okada;K. Matsuda
实验观察到，稳定的trions具有大的结合能（1025 meV）在原子薄的单层二维过渡金属dichalcogenides MX2（M = Mo，W，X = S，Se，和Te）具有各向同性的晶体结构已被广泛研究。相比之下，具有各向异性晶体结构的原子级薄2D材料中的trions的特性尚未完全理解。描述了通过施加栅极电压在具有各向异性晶体结构的少层ReS 2中的低温光致发光（PL）光谱。在通过调整栅极电压获得的中性激子的较低能量侧下方出现的新PL峰归因于来自负三重子的发射。此外，强烈依赖于层厚度的trion结合能在1 L-ReS 2中达到1060 meV的大值，其是其他各向同性2D材料（MX2）中的102倍。结合能的增强反映了各向异性原子薄ReS 2中trions的准一维性质。这些实验观察将促进对光学响应的更好理解以及在具有准一维性质的各向异性原子薄2D材料的新类别中的应用。
Experimentally observed, stable trions with large binding energy (≈25 meV) in atomically thin monolayer 2D transition metal dichalcogenides MX2 (M = Mo, W, X = S, Se, and Te) with an isotropic crystal structure have been extensively studied. In contrast, the characteristics of trions in atomically thin 2D materials with an anisotropic crystal structure are not completely understood. Low‐temperature photoluminescence (PL) spectroscopy in few‐layer ReS2 with an anisotropic crystal structure by applying a gate voltage is described. A new PL peak that emerges below the lower‐energy side of neutral excitons obtained by tuning the gate voltages is attributed to emission from negative trions. Furthermore, the trion binding energy that is strongly dependent on the layer thickness reaches a large value of ≈60 meV in 1L–ReS2, which is ≈2 times larger than that in other isotropic 2D materials (MX2). The enhancement of the binding energy reflects the quasi‐1D nature of the trions in anisotropic atomically thin ReS2. These experimental observations will promote a better understanding of the optical response and applications in new categories of the anisotropic atomically thin 2D materials with a quasi‐1D nature.