# Ge(111)-c(2x8) and Sn/Ge(111)-sqrt3 x sqrt3 Surfaces Studied by STM

University essay from Karlstads universitet/Fakulteten för hälsa, natur- och teknikvetenskap (from 2013)

Keywords: ;

Abstract: This experiment has used low-electron diffraction and scanning-tunneling microscopy to investigate the atomic and electronic structure of the Ge(111)-c(2x8) and Sn/Ge(111)-$\sqrt[]{3}\times\sqrt[]{3}$ surfaces. The clean Ge(111)-c(2x8) surface showed to have a weak diffraction pattern in LEED experiments. STM studies showed that large areas on the surface had lost it periodic structure and picked up dirt particles. On areas where the surface structure still remained it could be showed that partial charge transfer from adatoms to rest atoms occurs and therefore fills empty-states of the rest atom dangling bonds. The LEED experiment on Sn/Ge(111)-$\sqrt[]{3}\times\sqrt[]{3}$ proved to have a clear $\sqrt[]{3}\times\sqrt[]{3}$ diffraction pattern. STM investigations showed that the surface was flat and had well-defined structure over larger regions. Defects on the surface were mostly Ge substitutional atoms. Images taken in filled and empty-states have the same contrast leading to the conclusion that each Sn surface atom has a half filled dangling bond surface state.