First-principles simulation of STM/STS of Si(100) reconstructed surfaces

Abstract

The STM images and the STS spectra of silicon (100) reconstructed surfaces are theoretically simulated by the first-principles local density approximation (LDA) method and the tunneling Hamiltonian formalism. A new method for evaluating a tail of the surface wave function, which is important for tunneling of electrons, is also employed. Our simulation shows that the symmetric dimer structure seems to reproduce STM images of occupied states, but it cannot reproduce STM images of unoccupied states or STS spectra. On the other hand, simulations of all asymmetric dimer structures reproduce STS spectra in the seemingly symmetric dimer region as well as the zigzag dimer row patterns of the STM images. These results imply that observed symmetric images by STM may be asymmetric dimer structures.