Effect of stacking orientation on the electronic and optical properties of 2D nitride heterostructures

Given the successful synthesis of 2D GaN and investigations into the properties of freestanding 2D nitrides, heterostructures of these materials are now of particular interest. Extreme quantum confinement is a viable method to shift light emission to shorter wavelengths, but in 2D nitrides this is counteracted by the quantum-confined Stark shift due to the strong inherent polarization perpendicular to the 2D plane. We report the electronic and optical properties of 2D BN, GaN, AlN, and InN in various stacking orientations, such that the electric fields are either aligned or anti-parallel in two possible configurations. We employ density functional theory and quasiparticle corrections with the GW method, as well as the Bethe-Salpeter Equation, to derive accurate band structures, exciton binding energies, and luminescence energies. Through understanding how the stacking arrangement influences the underlying electronic and optical properties, critical insight will be gained in how to improve 2D III-nitride-based optoelectronics through accessing the additional degree of freedom provided by polarization.