Optical and Electronic Structural Properties of Cu3N Thin Films: A First-Principles Study (LDA + U)

摘要

A comprehensive study on the electronic structure and optical properties of a Cu_(3)N film is performed by the first-principles study using density functional theory. The Hubbard (U ) term is added in the local density approximation approach for improvement of the theoretical band gap energy. The band structure of the Cu_(3)N unit cell shows a strong hybridization of Cu 3d and N 2p orbitals in the near-valence band region (M ) because of their antibonding states which are also observed by molecular orbitals (HOMO–LUMO). The conduction band is dominated by a very small amount of Cu 3p and N 2p orbitals. The density of states exhibits a negligible deformation in Cu–N bonding. The Cu_(3)N thin film deposited by the DC magnetron-sputtering technique shows a polycrystalline structure with a nonstoichiometric Cu_(3)N phase. The experimentally obtained optical band gap and refractive index of the Cu_(3)N film are 1.44 eV and 2.14, respectively, which are comparable with those from the theoretical approximation.