Few layer epitaxial germanene: a novel two-dimensional Dirac material

Abstract

Monolayer germanene, a novel graphene-like germanium allotrope akin to silicene has been recently grown on metallic substrates. Lying directly on the metal surfaces the reconstructed atom-thin sheets are prone to lose the massless Dirac fermion character and unique associated physical properties of free standing germanene. Here, we show that few layer germanene, which we create by dry epitaxy on a gold template, possesses Dirac cones thanks to a reduced interaction. This finding established on synchrotron-radiation-based photoemission, scanning tunneling microscopy imaging and surface electron diffraction places few layer germanene among the rare two-dimensional Dirac materials. Since germanium is currently used in the mainstream Si-based electronics, perspectives of using germanene for scaling down beyond the 5 nm node appear very promising. Other fascinating properties seem at hand, typically the robust quantum spin Hall effect for applications in spintronics and the engineering of Floquet Majorana fermions by light for quantum computing.

Dirac Signature in Germanene on Semiconducting Substrate

“…The energy gap of the two peaks in each group is a constant value, indicating that the two fitting peaks in one group are related to two Ge 3 d 3/2 and 3 d 5/2 peaks, respectively. The Ge 3 d 5/2 spectrum appears as two peaks, 29.34 and 28.96 eV, both of which are close to that measured for germanene on Au(111)8 and germanene on Al(111) 43, 44. Thus, the peaks in Ge1 group and Ge2 group are assigned to Ge—Ge bonds in bulk Ge(111) and Ge—Ge bonds in √3 × √3 germanene, respectively.…”

Electronic and optical properties of bilayer blue phosphorus

“…After the discovery of graphene [1], other 2D nano-structures were predicted theoretically [2][3][4] and synthesized in laboratory [5][6][7]. Among these, the monolayer black phosphorus, 2D puckered structure of phosphorus, which was also successfully fabricated in laboratory [8,9] and studied with several theoretical works [10][11][12][13][14][15][16].…”

Electrochemical Formation of Germanene: pH 4.5

“…27 Moreover, the same investigators reported formation of a few layers thick germanene structures with the same atomic distances (0.256 nm) and steps heights of about 0.32 nm. 28 A (3 × 3) superstructure with similar interatomic distances was also observed on Al(111). The height of the germanene layer was found to be about 0.27 nm.…”