First Principle Study of the Optical Properties of Transition Metal Nitrides XN (X=Ti, Zr, Hf)

Abstract

The optical properties of face-centered cubic IVB group transition metal nitrides such as TiN, ZrN, and HfN were calculated using the plane wave pseudopotential method based on first-principle density function theory. The results of band structures show that conduction bands are mainly formed by the metal atom d-state, whereas valence bands are mainly formed by the N 2p-state. In optical properties research, the computed results of complex dielectric functions, absorptions, reflectivities, conductivities and loss functions of the three materials are analysed in terms of band structures. The results agree with experiment data. Analysis results show that the optical properties of these materials in low-energy regions are metallic because of the free electrons intraband-transition, and the transit to semiconducting properties in high-energy area is caused by valence electrons interband-transition. The sharp peaks of the transmissivity spectra indicate excellent optical selectivity in the visible light area. Moreover, lowering the starting energies of interband-transitions as a possible method to improve optical selectivities is discussed