期刊
NANO LETTERS
卷 17, 期 10, 页码 6360-6365出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b03184
关键词
Transition metal dichalcogenides; van der Waals heterostructures; interlayer exciton; chemical vapor deposition; valley polarization
类别
资金
- ANR JCJC project milliPICS
- Region Midi-Pyrenees [MESR 13053031]
- IDEX Toulouse
- Programme des Investissements d'Avenir [ANR-11-IDEX-0002-02, ANR-10-LABX-0037-NEXT]
- PAN-CNRS within PIGS
- Chinese Scholarship Council (CSC)
- Swiss SNF Sinergia [147607]
- Marie Curie ITN network MoWSeS [317451]
- National Science Center of Poland [DEC-2013/10/E/ST3/00034]
Stacking atomic monolayers of semiconducting transition metal dichalcogenides (TMDs) has emerged as an effective way to engineer their properties. In principle, the staggered band alignment of TMD heterostructures should result in the formation of interlayer excitons with long lifetimes and robust valley polarization. However, these features have been observed simultaneously only in MoSe2/WSe2 heterostructures. Here we report on the observation of long-lived interlayer exciton emission in a MoS2/MoSe2/MoS2 trilayer van der Waals heterostructure. The interlayer nature of the observed transition is confirmed by photoluminescence spectroscopy, as well as by analyzing the temporal, excitation power, and temperature dependence of the interlayer emission peak. The observed complex photoluminescence dynamics suggests the presence of quasi-degenerate momentum-direct and momentum-indirect bandgaps. We show that circularly polarized optical pumping results in long-lived valley polarization of interlayer exciton. Intriguingly, the interlayer exciton photoluminescence has helicity opposite to the excitation. Our results show that through a careful choice of the TMDs forming the van der Waals heterostructure it is possible to control the circular polarization of the interlayer exciton emission.
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