Graphene/g-GeC bilayer heterostructure: Modulated electronic properties and interface contact via external vertical strains and electric field

Using DFT calculations, we perform the modulated electronic properties and interface contact in the graphene/GeC heterostructure by tuning the interlayer spacing, along with the application of an external electric field. The graphene/GeC interface is examined to be dominated by the van der Waals (vdW) force with equilibrium interlayer spacing of 3.413 Å and binding energy per C atom of approximately −50 meV. This indicates graphene/GeC nanostructure a type of vdW heterostructure (vdWH). A direct band gap up to 6 meV is opened at the Dirac point, with the Dirac point well preserved, suggesting its significant application as a suitable candidate in nano-electronic and optoelectronic devices. Moreover, the graphene/GeC vdWH forms a p-type Schottky contact at the equilibrium state with a Schottky barrier height (SBH) of 0.14 eV. A transition for the interface contact from Schottky to Ohmic can be achieved by modifying the interlayer spacing smaller than 3.20 Å or applying a positive electric field of 0.1–0.7 V Å ⁻¹ . Interestingly, the p-type SBH (1.00 eV) can be tailored extensively approaching to the n-type SBH (1.09 eV) when negative electric field strengthened to 0.63 V Å ⁻¹ , demonstrating it substantial potential for the transition of Schottky contact from p-type to n-type. The findings are crucial for designing new nano-electronic devices comprising graphene-based vdWHs, which ascribes to the feasibility for application of tunable vertical strain and electric field in industrial applications.