Real-space imaging of single-layerMoS2by scanning tunneling microscopy

Abstract

Single layers of ${\mathrm{MoS}}_2$ have been studied with a scanning tunneling microscope operating in air. The images obtained from films that were prepared by depositing an aqueous suspension of single-layer ${\mathrm{MoS}}_2$ on a graphite surface show that the unit cell of the single layers corresponds to an approximate 2${\mathit{a}}_0$×${\mathit{a}}_0$ superlattice of the hexagonal 2H-${\mathrm{MoS}}_2$ structure. The unit-cell parameters, in conjunction with previous measurements, imply that the single layers of ${\mathrm{MoS}}_2$ adopt a distorted octahedral structure. The image of dry restacked ${\mathrm{MoS}}_2$ transforms back to the hexagonal ${\mathrm{MoS}}_2$ pattern.