Surface potential and interlayer screening effects of few-layer MoS ₂ nanoflakes

We report the interlayer screening effects of ultrathin MoS₂ nanoflakes with different thicknesses by measuring their surface potential using Kelvin probe microscope. Surface potential of pristine MoS₂ nanoflakes decreased with increasing thickness, while after annealing, the trend was opposite and the screening length became smaller. These results were qualitatively explained by a charge transfer model with the built-in electric field induced by trapped charges. The transport mechanism of MoS₂ nanoflakes with different thicknesses was also studied by using conductive atomic force microscopy, and the thermonic emission and Fowler-Nordheim tunneling were effective in the forward bias and reverse bias, respectively.