Patterning germanene into superlattices: An efficient method for tuning conducting properties

- Nanopatterning germanene into superlattices could open bandgap.
- Bandgap can be opened by the mechanism of breaking sublattice equivalence.
- Dirac cone folding to Γ in some germanene superlattices forms four-fold degeneracy.
- Novel mechanism of four-fold degeneracy perturbation can open bandgap accordingly.
- Gap width could be decreased by reducing the defect density in germanene.