Surface-dominant transport properties in MoSe₂ nanosheets

The electronic transport and photoconduction properties of the molybdenum diselenide (MoSe₂) nanosheets were investigated. The transfer length method analysis suggests the electric current following an anomalously two-dimensional (2D) flow rather than the general 3D mode. The 2D current implies a higher electron concentration and downward band bending at the surface. A broad spectral photoresponse from ultraviolet to near-infrared wavelengths was also observed for the MoSe₂ nanosheets. The optimal responsivity and photoconductive gain respectively at 58 A/W and 179 under the wavelengths at 405 nm were achieved. A surface-controlled photoconduction mechanism based on the surface band bending and electron accumulation is proposed to explain the long carrier lifetime and its dependence of light intensity and environment in MoSe₂ nanostructures.