Inhomogeneous band bending on MoS2(0001) arising from surface steps and dislocations.

We study the observed inhomogeneous band bending effects on cleaved MoS(2)(0001) single-crystal surfaces. Both Mo 3d and S 2p core levels were found to shift to lower binding energy in regions of the MoS(2) crystal with high step densities, as suggested by spot splitting of the LEED (low energy electron diffraction) pattern. Surface electronic band structure measurements also reveal a rigid shift of the valence bands in these regions, resulting from local Fermi level pinning effects. A surface electric field gradient on the MoS(2) crystals caused by the charged dislocations from the regions of high step densities generated by the cleaving process is found to explain most of the experimental observations.