First-principles calculations to investigate strain-tunable electronic bandgap of black phosphorus-structured nitrogen with desirable optical and elastic properties

Abstract

In this paper, structural and dynamic stabilities, elastic behavior, and electronic/optical properties of the layered polymeric nitrogen (LP-N) structure are investigated using density functional theory (DFT) calculations based on the generalized gradient approximation (GGA)/Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. The achievement of a structure under a pressure of 141 GPa with minimum energy and the absence of negative frequencies in its phononic dispersion curves confirm the possibility of the existence and stability of this novel material. We applied uniaxial loads along the zigzag, armchair, and interlayer directions of the LP-N, and according to the results, this structure has clear anisotropic elastic properties. The outcomes reveal that LP-N is stiffer along the zigzag direction than the armchair and interlayer directions. Also, its electronic band structures and density of states show a direct bandgap of 0.05 eV confirming its semiconductor nature, while LP-N with a larger direct bandgap of 0.7 eV was obtained by imposing strain along the zigzag direction. Tunable electronic and optical properties of LP-N under external stresses make it a proper choice for high-pressure optoelectronic applications.