posted on 2022-12-09, 16:42authored byYoseob Yoon, Zuocheng Zhang, Ruishi Qi, Andrew Y. Joe, Renee Sailus, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, Feng Wang
Ultrafast charge transfer processes provide a facile
way to create
interlayer excitons in directly contacted transition metal dichalcogenide
(TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD
enable new ways to control interlayer exciton properties and achieve
novel exciton phenomena, such as exciton insulators and condensates,
where longer lifetimes are desired. In this work, we experimentally
study the charge transfer dynamics in a heterostructure composed of
a 1 nm thick hBN spacer between MoSe2 and WSe2 monolayers. We observe the hole transfer from MoSe2 to
WSe2 through the hBN barrier with a time constant of 500
ps, which is over 3 orders of magnitude slower than that between TMD
layers without a spacer. Furthermore, we observe strong competition
between the interlayer charge transfer and intralayer exciton–exciton
annihilation processes 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.