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Experimental Evidence of Anisotropic and Stable Charged Excitons (Trions) in Atomically Thin 2D ReS 2
Author(s) -
Wang Xiaofan,
Shinokita Keisuke,
Miyauchi Yuhei,
Cuong Nguyen Thanh,
Okada Susumu,
Matsuda Kazunari
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201905961
Subject(s) - trion , materials science , anisotropy , binding energy , exciton , photoluminescence , isotropy , monolayer , condensed matter physics , thin film , crystal (programming language) , atomic physics , nanotechnology , optoelectronics , optics , physics , computer science , programming language
Experimentally observed, stable trions with large binding energy (≈25 meV) in atomically thin monolayer 2D transition metal dichalcogenides MX 2 (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 ReS 2 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–ReS 2 , which is ≈2 times larger than that in other isotropic 2D materials (MX 2 ). The enhancement of the binding energy reflects the quasi‐1D nature of the trions in anisotropic atomically thin ReS 2 . 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.