Large exciton-driven linear and nonlinear optical processes and band nesting in monolayers of nitrogen arsenide and nitrogen antimonide
Creators: name: Author(s), Unknown
Publisher: name: figshare
Year: 2022
Subjects: subject: 30301 Chemical Characterisation of Materials
subject: FOS: Chemical sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: 30404 Cheminformatics and Quantitative Structure-Activity Relationships
subject: Computational Chemistry
subject: Inorganic Chemistry
subject: 30299 Inorganic Chemistry not elsewhere classified
subject: 30399 Macromolecular and Materials Chemistry not elsewhere classified
subject: 30303 Optical Properties of Materials
subject: 30699 Physical Chemistry not elsewhere classified
subject: 30304 Physical Chemistry of Materials
subject: 30701 Quantum Chemistry
subject: 30702 Radiation and Matter
subject: 30206 Solid State Chemistry
subject: 30606 Structural Chemistry and Spectroscopy
subject: 30799 Theoretical and Computational Chemistry not elsewhere classified
subject: 30307 Theory and Design of Materials
subject: Applied Physics
subject: Computational Physics
subject: 20403 Condensed Matter Modelling and Density Functional Theory
subject: FOS: Physical sciences
subject: Condensed Matter Physics
subject: 20499 Condensed Matter Physics not elsewhere classified
subject: 20502 Lasers and Quantum Electronics
subject: 20503 Nonlinear Optics and Spectroscopy
subject: 20599 Optical Physics not elsewhere classified
subject: 20504 Photonics, Optoelectronics and Optical Communications
subject: 29999 Physical Sciences not elsewhere classified
subject: Quantum Mechanics
subject: 20604 Quantum Optics
subject: 20699 Quantum Physics not elsewhere classified
subject: 20406 Surfaces and Structural Properties of Condensed Matter

description: We demonstrate that atomically thin nitrogen-based binary group-V wide band-gap indirect semiconductors (NX (X=As, Sb)) can show strong linear and nonlinear optical activities. Contrary to NAs, we find that the fundamental optical absorption in NSb is infact quite resilient towards the temperature variations between 0-450 K. Exciton in NSb is however found to be less strongly bound (1.40 eV) compared to the more tight case in NAs (1.63 eV), leading to a more delocalised Mott-Wannier type texture. The inhomogenous excitonic linewidths for both monolayers within these temperatures are found to be in the range of 100-400 meV. The largest nonlinear second harmonic optical coefficient (2$\omega$ resonances) in NAs and NSb monolayers are obtained to be $\sim$270 and 636 pm/V at 2.6 eV (477 nm) and 3.2 eV (387 nm) respectively. We also provided a detailed analysis of in-plane biaxial strain on these structures. We found that a tensile strain is energetically more favorable and does not influence the exciton binding energy in NAs. The nonlinear coefficient also significantly improves at the two most important 810 and 1560 nm wavelengths compared to the cases offered by the monolayer transitional metal dichalcogenides. Our analysis is based on a fully $ab$-$initio$ G$_0$W$_0$+Bethe-Salpeter excited state theory. The temperature-dependent linear absorption spectra are evaluated by including the electron-phonon self-energies, whereas the nonlinear spectra are treated using the modern theory of polarization within the same perturbative approach.