Nanometer-Scale Imaging

This chapter discusses the imaging mechanism of STM at the nanometer scale, where the features of interest are of about one nanometer and up. Using an s-wave tip model, using the Bardeen tunneling theory, Tersoff and Hamann showed that the STM image in this case is tip-independent: it is determined by the local density of states of the bare sample surface at Fermi level, taken at the center of curvature of the tip. The Tersoff-Hamann model has found numerous applications in interpreting the STM images, from the superstructure of surface reconstruction to the confined or scattered waves of the surface states. However, as shown by Tersoff and Hamann in their original papers, for features much smaller than one nanometer, such as at the atomic features of 0.3 nm, the non-spherical electronic states of the tip could play a significant role and thus cannot be overlooked.

Scanning tunneling microscopy and Raman evidence of silicene nanosheets intercalated into graphite surfaces at room temperature

(a) STM image of a graphite (G) substrate after the Si deposition at RT. (b) Stable configuration of a silicene nanosheet intercalated under the outmost G layer and (c) this outmost G layer distribution of the tensile strain.

Computational insight into the origin of unexpected contrast in chiral markers as revealed by STM

Chiral substituents in self-assembled molecular layers show differences in bias dependence in STM image contrast.