First Principles Study Of3d Transition Metal Doped Copper Nitride

Copper nitride (Cu3N) thin film, as a semiconducting material, is metastable at room temperature.It has characteristics of low decomposition temperature of300-450℃, high resistivity and lowreflectance in the infrared and visible band. In recent years, copper nitride, as a new material, hasbeen attractive for its applications in the field of the storage and microelectronic semiconductorphotoelectric. The ordered structure of Cu3N was of anti-ReO3type in the Pm3m (221) space group.Copper atoms occupy the center of the cubic edges and nitrogen atoms occupy the corners of thecell. This arrangement is peculiar since Cu atoms do not occupy the face-centered cubicclose-packing sites. So there are many vacant interstitial sites in this crystal structure. If additionalcopper or other atoms are contained within these sites, the electrical and optical properties of thedoped copper nitride are different from those of the ideal Cu3N.This paper investigated the properties of3d transition metal doped Cu3N (Cu3NM: M=Sc, Ti, V,Cr, Mn, Fe, Co, Ni), by using the first-principles method which based on the density functionaltheory (DFT), and carrying out with the WIEN2k package. Firstly, the structures of Cu3N and dopedstate Cu3NM were optimized to get the most suitable lattice constant. Then we calculated thedensity of states (DOS), band structure, electron density, elastic constants and elastic modulus ofCu3N and Cu3NM. The results show that:(1) Transition metal atom-doped Cu3N unit cell with an extra M atom at the center of the cubeleaded to the volume expansion and shrinkage with the increasing the atomic number of dopedatoms. Mn atom is a critical point;(2) All the transition metal atoms intercalate into cubic Cu3N change semiconductor to be conductor.Optical band gap no longer exists. DOS and electron density show that by increasing the electronsin3d orbit of doped atom, the strong hybridization become stronger between Cu3d and doped atom3d electron. Doping atoms weaken the interaction between Cu-N bonds.(3) Cohesive energy calculation show that it is easier to get3d transition doped Cu3N than pureCu3N in the lab. Elastic properties shows that Cu3NM are mechanical stable and all the compoundscan be classified into the malleable material.