We have investigated the growth of Pt on Ge(110) using scanning tunneling microscopy and spectroscopy. The deposition of several monolayers of Pt on Ge(110) followed by annealing at 1100 K results in the formation of three-dimensional metallic Pt-Ge nanocrystals. The outermost layer of these crystals exhibits a honeycomb structure. The honeycomb structure is composed of two hexagonal sub-lattices that are displaced vertically by 0.2 {\AA} with respect to each other. The nearest-neighbor distance of the atoms in the honeycomb lattice is 2.5±0.1 {\AA}, i.e. very close to the predicted nearest-neighbor distance in germanene (2.4 {\AA}). Scanning tunneling spectroscopy reveals that the atomic layer underneath the honeycomb layer is more metallic than the honeycomb layer itself. These observations are in line with a model recently proposed for metal di-(silicides/)germanides: a hexagonal crystal with metal layers separated by semiconductor layers with a honeycomb lattice. Based on our observations we propose that the outermost layer of the Ge2Pt nanocrystal is a germanene layer.
@article{arxiv.1706.00697,
title = {Germanene termination of Ge${_2}$Pt crystals on Ge(110)},
author = {P. Bampoulis and L. Zhang and A. Safaei and R. van Gastel and B. Poelsema and H. J. W. Zandvliet},
journal= {arXiv preprint arXiv:1706.00697},
year = {2017}
}