Charge Transfer\nDynamics in MoSe₂/hBN/WSe₂ Heterostructures

Abstract

Ultrafast charge transfer processes provide a facile\nway to create\ninterlayer excitons in directly contacted transition metal dichalcogenide\n(TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD\nenable new ways to control interlayer exciton properties and achieve\nnovel exciton phenomena, such as exciton insulators and condensates,\nwhere longer lifetimes are desired. In this work, we experimentally\nstudy the charge transfer dynamics in a heterostructure composed of\na 1 nm thick hBN spacer between MoSe₂ and WSe₂ monolayers. We observe the hole transfer from MoSe₂ to\nWSe₂ through the hBN barrier with a time constant of 500\nps, which is over 3 orders of magnitude slower than that between TMD\nlayers without a spacer. Furthermore, we observe strong competition\nbetween the interlayer charge transfer and intralayer exciton–exciton\nannihilation processes at high excitation densities. Our work opens\npossibilities to understand charge transfer pathways in TMD/hBN/TMD\nheterostructures for the efficient generation and control of interlayer\nexcitons.