root 3 x root 3 germanene on Al(111) grown at nearly room temperature

A root 7 x root 7-R19.1 degrees superstructure has been formed on Al(111) by Ge deposition at nearly room temperature, which is different from the previously reported germanene on Al(111) with 3 x 3 periodicity. By scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory calculation, the atomic structure of this surface is predicted to be a root 3 x root 3 periodic honeycomb lattice of Ge atoms formed on Al(111) root 7 x root 7, in which one Ge atom per unit cell markedly protrudes into the vacuum side. The calculated band structure based on the predicted germanene/Al(111)root 7 x root 7 structure indicates strong hybridization between the Ge layer and the Al( 111) substrate. (C) 2018 The Japan Society of Applied Physics