Proximity-driven metallization of germanene on NiTe2 via interfacial coupling

Abstract

Epitaxial germanene layers have been grown on a NiTe2 substrate, and their structural and electronic properties were systematically investigated using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. The as-grown germanene exhibits a honeycomb structure with a lattice constant of 3.9 Å and a (1 × 1) structure relative to the substrate lattice. The differential conductivity shows a V-shaped profile, characteristic of a two-dimensional Dirac system, with its minimum lying close to the Fermi level yet remaining non-zero. By combining STM observations with first-principles calculations, we attribute this phenomenon to charge transfer between the NiTe2 substrate and germanene, thereby leading to the emergence of a metallic state in germanene. This finding provides a valuable framework for understanding the interplay between structural and electronic properties in this system. Furthermore, these results lay a solid foundation for exploring potential applications of germanene and open up promising avenues for future research.