We report ultrafast pump-probe measurements on a graphene/MoS2 heterostructure and demonstrate sub picosecond exciton dissociation and charge transfer from MoS2 to graphene, one order of magnitude faster than in type II two-dimensional heterostructures. The process can be controlled by applying an external gate and shifting the Fermi level of graphene. For pump-probe measurements we excite the gate controlled graphene/MoS2 heterostructure at 400 nm, well above the MoS2 bandgap, and probe the normalized differential transmission changes (ΔT/T) of the MoS2 first exciton (A exciton) at 660nm with time resolution~200fs. In this configuration, MoS2 acts as the absorbing material for visible wavelengths while graphene is the electron scavenger.
Gate tuneable ultrafast charge transfer in graphene/MoS2 heterostructures
De Fazio D;
2017-01-01
Abstract
We report ultrafast pump-probe measurements on a graphene/MoS2 heterostructure and demonstrate sub picosecond exciton dissociation and charge transfer from MoS2 to graphene, one order of magnitude faster than in type II two-dimensional heterostructures. The process can be controlled by applying an external gate and shifting the Fermi level of graphene. For pump-probe measurements we excite the gate controlled graphene/MoS2 heterostructure at 400 nm, well above the MoS2 bandgap, and probe the normalized differential transmission changes (ΔT/T) of the MoS2 first exciton (A exciton) at 660nm with time resolution~200fs. In this configuration, MoS2 acts as the absorbing material for visible wavelengths while graphene is the electron scavenger.
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