Symmetry breaking induced bandgap opening in epitaxial germanene on WSe2

Abstract

Germanene has attracted much attention because the material was predicted to host Dirac fermions. However, the synthesis of germanene is still in its infancy; moreover, the predicted tiny bandgap induced by the spin–orbit coupling is far from practical applications for nanoelectronic devices. Herein, quasi-freestanding germanene with linear dispersion relation of the band structure is well grown on a WSe2/Au(100) substrate. Band structure calculations reveal that the interaction of germanene with the substrate destroys the sublattice symmetry. The energy-dependent contribution of σ orbitals responsible for band crossing at the Fermi level around the Γ point induces asymmetric density of states at the Dirac point. Upon annealing in ultra-high vacuum, we observe a bandgap opening in germanene of about ∼0.17 eV, which is attributed to a sublattice symmetry breaking in germanene and the emergence of a net electric field. This work provides an effective method to tune or tailor the electronic properties of germanene, paving the way to germanene-based field-effect applications.

Massive and massless plasmons in germanene nanosheets

“…In the present study, we have singled out the additional versatility of germanene monolayers and related interfaces 87 , whose multiple light-matter modes are strongly dependent on both geometry and charge carrier concentration. We remark that the latter is a novel feature, which marginally involve other 2DDMs, and as such it requires an improved analysis, in line with what has been reported here, for a correct tuning of the input parameters of possible germanene-based devices.…”

Massive and massless plasmons in germanene nanosheets

“…In the present study, we have singled out the additional versatility of germanene monolayers and related interfaces 87 , whose multiple light-matter modes are strongly dependent on both geometry and charge carrier concentration. We remark that the latter is a novel feature, which marginally involve other 2DDMs, and as such it requires an improved analysis, in line with what has been reported here, for a correct tuning of the input parameters of possible germanenebased devices.…”

Monolayers of Germanene/Janus Ga2SeTe van der Waals Heterostructures by First-Principles Calculations for High-Performance Optoelectronic Devices

“…Hoat et al 17 proposed an effective approach to manually creating the band gap of Ge by chemical functionalization and doping of Ge with halogen atoms. Wu et al 18 demonstrated that a sizable band gap in Ge can be opened by controlling the interaction between Ge and the substrate both experimentally and theoretically. Ge more easily opens the Dirac cone band gap than graphene, which can bring more special physical properties.…”