Charge transfer dynamics in MoSe$_{2}$/hBN/WSe$_{2}$ heterostructures

Kavli Affiliate: Feng Wang

| First 5 Authors: Yoseob Yoon, Zuocheng Zhang, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay

| Summary:

Ultrafast charge transfer processes provide a facile way to create interlayer
excitons and to generate single-cycle THz pulses in directly contacted
transition metal dichalcogenide (TMD) layers. More sophisticated
heterostructures composed of TMD/hBN/TMD can enable new ways to control the
charge transfer dynamics to achieve novel exciton phenomena, such as exciton
insulators and exciton condensates, where longer lifetimes are desired. In this
work, we experimentally study charge transfer dynamics in a heterostructure
composed of a 1-nm-thick hBN spacer between MoSe$_{2}$ and WSe$_{2}$
monolayers. We observe the interlayer charge transfer from MoSe$_{2}$ to
WSe$_{2}$ across hBN with a time constant of 500 ps, which is over three orders
of magnitude slower compared to the charge transfer between TMD layers without
an hBN spacer. Furthermore, we observe strong competition between the
interlayer charge transfer process with the intralayer exciton-exciton
annihilation process at high excitation densities. Our work opens possibilities
to understand charge transfer pathways in TMD/hBN/TMD heterostructures for the
efficient generation and control of interlayer excitons.

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