Raman spectroscopy of the interlayer shear mode in few-layer MoS2 flakes

摘要

Single- and few-layer MoS2 has recently gained attention as an interestingnew material system for opto-electronics. Here, we report on scanning Ramanmeasurements on few-layer MoS2 flakes prepared by exfoliation. We observe aRaman mode corresponding to a rigid shearing oscillation of adjacent layers.This mode appears at very low Raman shifts between 20 and 30 relativewavenumbers. Its position strongly depends on the number of layers, which weindependently determine using AFM measurements and investigation of the othercharacteristic Raman modes. Raman spectroscopy of the shear mode therefore is auseful tool to determine the number of layers for few-layer MoS2 flakes.