Predicting the structures and properties of few-layer two-dimensional (1 1 0)-oriented BN nanosheets: First-principles calculations

Abstract

Based on first-principles calculations, we investigate the structural, electronic and optical properties of few-layer two-dimensional (2D) (1 1 0)-oriented BN nanosheets in relation to the layer number (n). After structural optimization, for n = 1 and n = 2, the buckling 2D BN nanosheets are reconstructed into planar sheets. With an increasing layer number n ≥ 3, the original bulk c-BN structures are energetically favorable to being maintained, and their properties tend to stabilize. It is demonstrated that the minimum number of layers that can satisfy the cubic phase structure of the (1 1 0) surface is 3; the thickness is approximately 5 Å. What is more interesting is that there are characteristics of the electronic and optical properties that are distinct from those of bulk c-BN material; the band gap and static refractive index values decrease to nearly half of those of the bulk material when the dimension changes from 3D to 2D. The development of novel structures in BN material fields is of great significance for both basic science and practical industrial applications.