Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 46: 2D semiconductors and van der Waals heterostructures IV (joint session HL/DS/O)

O 46.5: Talk

Tuesday, March 17, 2020, 15:00–15:15, POT 81

Efficient Hot Electron Transfer at Graphene-WS2 van der Waals Bilayers — SHuai Fu and •Hai Wang — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Hybridization of (semi-)metallic and semiconducting monolayers, such as graphene and layered transition metal dichalcogenides (TMDs), enables efficient and sensitive photodetectors, by combing the synergetic properties of strong absorption at exciton resonances in TMDs, efficient charge transfer cross the interfaces and ultrahigh charge mobility in graphene. In spite of the great advance in devices, the fundamental understanding of the mechanism underlying the ultrafast charge flow across the heterostructures lags far behind, and effective means of controlling its efficiency have not been established.

Employing Terahertz spectroscopy, we shed light on the fundamentals of ultrafast interfacial nonequilibrium dynamics in graphene-WS2 van der Waals bilayers. We report an efficient and ultrafast hot electron injection from graphene to WS2, which competes with hot carrier heating process in graphene. We will discuss the mechanism underlying the hot electron charge transfer process, and factors governing its efficiency and lifetime of interfacial charge states, which are critical for efficient optoelectronics (i.e. photodetectors) based on van der Waals heterostructures.