Uncovering New Buckled Structures of Bilayer GaN: A First-Principles Study

Abstract

New structures of bilayer GaN displaying buckling are revealed, and their structural and electronic properties are studied using first-principles calculations. Layered GaN is a promising two-dimensional material of the III-V family with a sizable band gap. The impact of buckling and the difference in atomic structure of the different models lead to significant changes in the electronic structure, including an indirect-to-direct band gap transition. Because of the small energy difference between different models, it can be expected that at room temperature, regions of the material may have different structures that coexist. The possibility to tailor the structural and electronic properties of bilayer GaN by applying an external strain is also explored. Under tensile strain, all structures tend to become flat, whereas under biaxial compressive strain, buckled structures are favored, with an indirect-to-direct band gap transition.