Investigation of the atomic and electronic structures of highly ordered two-dimensional germanium on Au(111)

TL;DR

This study uses LEED, STM, and photoelectron spectroscopy to analyze the atomic and electronic structures of a highly ordered germanium layer on Au(111), revealing new structural details and clarifying electronic band characteristics.

Contribution

It proposes a new atomic structure model for the Ge layer on Au(111) and clarifies the electronic band structure, refuting previous interpretations of a Dirac cone.

Findings

Identified a new unit cell for the Ge layer

Detected Ge atom diffusion into Au(111) during annealing

Excluded the presence of a Dirac cone in germanene electronic structure

Abstract

Low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and photoelectron spectroscopy have been used to study an ordered structure formed by Ge atoms deposited onto the Au(111) surface. Based on a careful analysis of STM images and LEED patterns, we propose a new unit cell for the atomic structure of the Ge layer. Core level data indicate that some Ge atoms diffuse into the Au(111) crystal during annealing after deposition at room temperature. This is further corroborated by angle resolved photoelectron spectroscopy measured for different amounts of Ge remaining after sputtering and annealing. The results of the ARPES study clearly exclude the interpretation, in the literature, of a parabolic band as part of a Dirac cone of germanene.