Germanene: a novel two-dimensional Germanium allotrope akin to Graphene and Silicene

TL;DR

This paper reports the synthesis and characterization of germanene, a novel two-dimensional germanium allotrope similar to graphene, grown on a gold substrate and confirmed through spectroscopy and theoretical calculations.

Contribution

It provides the first experimental evidence of germanene, a new 2D germanium material, using molecular beam epitaxy and advanced analysis techniques.

Findings

Identification of a germanene layer with a honeycomb structure

Observation of a $$x$$R(30°) germanene superstructure

Confirmation of germanene's similarity to graphene and silicene

Abstract

Using a gold (111) surface as a substrate we have grown in situ by molecular beam epitaxy an atom-thin, ordered, two-dimensional multi-phase film. Its growth bears strong similarity with the formation of silicene layers on silver (111) templates. One of the phases, forming large domains, as observed in Scanning Tunneling Microscopy, shows a clear, nearly flat, honeycomb structure. Thanks to thorough synchrotron radiation core-level spectroscopy measurements and advanced Density Functional Theory calculations we can identify it to a $\sqrt{3}$x$\sqrt{3}$R(30{\deg}) germanene layer in coincidence with a $\sqrt{7}$x$\sqrt{7}$R(19.1{\deg}) Au(111) supercell, thence, presenting the first compelling evidence of the birth of a novel synthetic germanium-based cousin of graphene.