Analysis of complex heterogeneous surfaces by bias-dependent scanning tunneling microscopy and spectroscopy

In this work we present analysis of various multicomponent surfaces, such as Si-Ge, Co-Ge and Co-Si, by combined bias-dependent scanning tunneling microscopy (STM) and spectroscopy (STS). Using the STM's capability for surface visualization with sub-nanometer resolution, and STS's capability to provide information directly linked to the surface density of states of these sub-nanometer regions, we were able to distinguish between such dissimilar nano-regions, some of which could only be revealed by bias-dependent STM imaging. The work emphasizes the need for a wider theoretical support in interpreting tunneling images and spectra.