Influence of the electric field on the electronic structure of flat hexagonal two-dimensional GaN bilayers

Two-dimensional gallium nitride materials have recently garnered significant attention due to their promising optoelectronic properties, chemical stability, and mechanical strength. These attributes make them attractive for various technological applications, particularly optoelectronics, photonics, sensors, and more recently for high-power electronic applications. Our research, using first-principles calculations based on density functional theory (DFT) considering different exchange-correlation functionals, including van der Waals interaction, investigated the electronic properties of a single GaN monolayer and five different stacking configurations of GaN bilayers. The aim is to characterize the electronic properties of 2D-GaN-based materials and explore the impact of external electric fields on the bilayer stacking bandgap. We report the energetically most favorable among the bilayer configurations analyzed. Additionally, we confirmed that it is possible to modulate the energy bandgap both by the type of bilayer stacking and by the effect of the electric field. The ability to tune the energy bandgap (Eg) in 2D-GaN-based materials by adjusting their geometric configuration or applying an external electric field could inspire new applications in various technological fields.