Structural, Electronic and Optical Properties of Sc<sub>x</sub>Al<sub>1-x</sub>N alloys within DFT Calculations

Abstract

Structural, electronic and optical properties of Sc-based aluminum-nitride alloy have been carried out with first-principles methods using both local density approximation (LDA) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. This latter provides a more accurate description of the lattice parameters, enthalpy of formation, electronic and optical properties of our alloy than standard DFT. We found the transition from wurtzite to rocksalt structures at 61% of Sc concentration. By increasing the scandium concentration, the lattice parameters and the band gap decrease. The HSE band gap is in good agreement with available experimental data. The existence of the strong hybridization between Sc 3d and N 2p indicates the transport of electrons from Sc to N atoms. Besides, it is shown that the insertion of the Sc atom leads to the redshift of the optical absorption edge. The optical absorption of Sc x Al 1−x N is found to decrease with increasing Sc concentrations in the low energy range. Because of this, Sc x Al 1−x N have a great potential for applications in photovoltaics and photocatalysis.