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Electron dynamics in MoS 2 -graphite heterostructures.

Authors :: Zhang X
He D
Yi L
Zhao S
He J
Wang Y
Zhao H
Source :: Nanoscale [Nanoscale] 2017 Oct 05; Vol. 9 (38), pp. 14533-14539.
Publication Year :: 2017
Abstract: The electron dynamics in heterostructures formed by multilayer graphite and monolayer or bulk MoS <subscript>2</subscript> were studied by femtosecond transient absorption measurements. Samples of monolayer MoS <subscript>2</subscript> -multilayer graphite and bulk MoS <subscript>2</subscript> -multilayer graphite were fabricated by exfoliation and dry transfer techniques. Ultrafast laser pulses were used to inject electron-hole pairs into monolayer or bulk MoS <subscript>2</subscript> . The transfer of these photocarriers to the adjacent multilayer graphite was time resolved by measuring the differential reflection of a probe pulse. We found that photocarriers injected into monolayer MoS <subscript>2</subscript> transfer to graphite on an ultrafast time scale shorter than 400 fs. Such an efficient charge transfer is key to the development of high performance optoelectronic devices with MoS <subscript>2</subscript> as the light absorbing layer and graphite as electrodes. The absorption coefficient of monolayer MoS <subscript>2</subscript> can be controlled by the carriers in graphite. This process can be used for interlayer coupling and control. In a bulk MoS <subscript>2</subscript> -graphite heterostructure, the photocarrier transfer time is about 220 ps, due to the inefficient interlayer charge transport in bulk MoS <subscript>2</subscript> . These results provide useful information for developing optoelectronic devices based on MoS <subscript>2</subscript> -graphite heterostructures.