Meta-GGA study of 2D AlN/BN planer heterostructure and performance enhancement via strain engineering.

contextThe 2D AlN/BN planer heterostructure is a promising wide band gap semiconductor, but systematic studies of its bandgap and optical characteristics under applied strain are scarce. Here, the engineering property of 2D AlN/BN comprising bandgap nature transition and optical absorption capability (from unstrained to strained) have been investigated using density functional theory calculations. The formation energy calculations confirm the stability of the simulated nanoheterostructure. The electronic band structure calculations demonstrate that nanoheterostructure is an indirect bandgap material with a large bandgap of 5.26 eV, which can be modified effectively by applying strain. According to the calculations, the transition from indirect to direct band gap behavior has been observed at +15% biaxial strain with 2.71 eV band gap energy. Meanwhile, calculations for optical absorption and dielectric function reveal that the system has significant absorption peaks in the ultraviolet region which are very sensitive to applied strain. As strain increases, the first absorption peaks are shifted towards a lower energy range from 5.73 eV (Ꜫ= 0 %) to 3.76 eV (Ꜫ = +15%), which features an enhancement of optical absorption for solar and solar-blind regions. Furthermore, we determined that the band edge positions in 2D AlN/BN straddled the water redox potential under strain, indicating its effectiveness as a proficient photocatalyst. These characteristics make 2D AlN/BN planer nanoheterostructure a promising candidate for applications in optoelectronics and photocatalytic water splitting performance.

methodsFirst principles computations based on density functional theory were employed to carry out all the calculations with a self-consistent approach. For solving the Kohn-Sham equations, the first principles dependent full-potential linearized augmented plane wave scheme were adopted. For addressing the exchange-correlation effects, the generalized gradient approximation of PBEsol functional was used. To prevent interaction between the periodic images, we have inserted a vacuum region of 10 Å in the z-direction. Non-negligible weak dispersion corrections in nanoheterostructure were considered by using the DFT-D3 method of Grimme's. The locally modified Becke-Johnson (lmBJ) exchange potential has also been applied to compute electronic and optical properties in this research to obtain more accurate information.