Germanene films on Au(111) and Al(111)

E. MARTÍNEZ; L. M. SOLIS; E. D. CANTERO; J. D. FUHR; M. L. MARTIARENA; O. GRIZZI; E. A. SANCHEZ

S. C. de Bariloche

Simposio; XXIII Latin American Symposium on Solid State Physics; 2018

Organizers of XXIII SLAFES

The scientific and technological revolution that started with the production of atomically-flat graphene has swiftly evolved to include research and development in other 2D materials from group-IV atoms. The fabrication of silicene, stanene and more recently germanene is a matter of great debate in the community due to their electronic and structural properties and possible applications. The interest on germanene films is centered on the electronic properties because of the presence of Dirac cones, and on its structure as it arranges on a buckled honeycomb lattice that may favor the adsorption of molecules and other materials. In this work we present a characterisation of Ge films grown on Au(111) and Al(111) by evaporation under UHV conditions. Surface crystallography and composition was analysed by means of several experimental techniques including Scanning Tunneling Microscopy (STM), Time-of-Flight Direct Recoil Spectrometry (TOF-DRS), Low Energy Electron Diffraction (LEED), Electron Energy Loss Spectroscopy (EELS), Ultraviolet Photoelectron Spectroscopy (UPS), and by comparison with Density Functional Theory (DFT) calculations. The LEED patterns indicate very well-ordered phases of the Ge films on both substrates. For Au(111) the STM also shows a big 5x8 unit cell but the formation of a honeycomb structure could not be unambiguously determined as proposed by different groups. Moreover, the high sensitivity of the TOF-DRS technique allowed us to show the presence of Au atoms in the Ge film and the diffusion of Ge atoms into the sample. On the other hand, the preliminary results obtained for the growth of less than a monolayer of Ge atoms on Al(111) show a 3x3 structure without diffusion of Ge atoms into the Al sample. The comparison of the results obtained in our laboratory with data reported in recent literature is also presented, analysing similarities and differences for both systems.