SCANNING PROBE MICROSCOPY STUDY OF LAYERED DICHALCOGENIDE RES2

The surface of the layered chalcogenide ReS2 was examined by atomic force microscopy (AFM) and scanning tunneling microscopy (STM), and the structure of ReS2 was determined by single crystal X-ray diffraction measurements. The observed atomic-resolution AFM and STM images were analyzed by calculating the total and partial electron density distributions [p(r(0)) and p(r(0),rho(f)), respectively] of a single ReS2 layer taken from the bulk crystal structure. Our results show that the STM images are associated with the surface S atoms. The p(r(0),rho(f)) plots of the two tunneling processes differ in topography from the p(r(0)) plot so that the surface atomic structure cannot be unambiguously deduced from the analysis of atomic-resolution STM images alone. Calculations of the p(r(0)) and p(r(0),rho(f)) plots are essential for properly interpreting the atomic-resolution AFM and STM images.