Single germanene phase formed by segregation through Al(111) thin films on Ge(111)

We have obtained single phase monolayer germanene on aluminum (111) thin films grown on a germanium (111) template by atomic segregation epitaxy, a preparation method differing from molecular beam epitaxy used in previous works. This 2 x 2 reconstructed germanene phase matching an Al(111)3 x 3 supercell has been prepared in large areas upon annealing at 430 degrees C. Detailed studies have been carried out using scanning tunneling microscopy (STM), low-energy electron diffraction, Auger electron spectroscopy, and synchrotron radiation photoemission spectroscopy. First-principles calculations based on the density function theory along with atomic-scale STM images reveal the atomic structure with one protruding Ge atom per 2 x 2 germanene supercell and a characteristic dispersing band originating from the germanene sheet slightly coupled to the first layer Al atoms underneath. Instead, upon annealing at lower temperatures, multi-phase regions comprise twisted germanene domains in correspondence with an Al(111)root 7x root 7 R +/- 19.1 degrees superstructure as obtained in previous studies.

Automated summary

In this study, single phase monolayer germanene has been successfully obtained on aluminum thin films using atomic segregation epitaxy, exhibiting unique structural characteristics that can be potentially explored for future research on its properties.