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Momentum-forbidden dark excitons in hBN-encapsulated monolayer MoS2

2019; Nature Portfolio; Volume: 3; Issue: 1 Linguagem: Inglês

10.1038/s41699-019-0108-4

2397-7132

Yosuke Uchiyama, Alex Kutana, Kenji Watanabe, Takashi Taniguchi, Kana Kojima, Takahiko Endo, Yasumitsu Miyata, Hisanori Shinohara, Ryo Kitaura,

MXene and MAX Phase Materials

Abstract Encapsulation by hexagonal boron nitride (hBN) has been widely used to address intrinsic properties of two-dimensional (2D) materials. The hBN encapsulation, however, can alter properties of 2D materials through interlayer orbital hybridization. In this paper, we present measurements of temperature dependence of photoluminescence intensity from monolayer MoS 2 encapsulated by hBN flakes. The obtained temperature dependence shows an opposite trend to that of previously observed in a monolayer MoS 2 on a SiO 2 substrate. This is caused by the existence of stable momentum-forbidden dark excitons in the hBN-encapsulated MoS 2 . Ab-initio band-structure calculations have shown that orbital hybridization between MoS 2 and hBN leads to upward shift of Γ-valley of MoS 2 , which results in lowering of energy of the momentum-forbidden dark excitons. This work shows an important implication that the hBN-encapsulated structures used to address intrinsic properties of two-dimensional crystals can alter basic properties of encapsulated materials.