Crystal structure and optical properties of silver-doped copper nitride films (Cu₃N:Ag) prepared by magnetron sputtering

Silver-doped copper nitride (Cu₃N:Ag) films were prepared by using radio frequency and a direct current magnetron sputtering method. The effects of silver doping on the crystal structure, surface morphology, and optical properties of the films were investigated. Results demonstrated that Ag doping influences the preferred growth orientation of the films. With the increased Ag content, the films grow from the (1 0 0) crystal face to the (1 1 1) crystal face. Ag doping changes the lattice constant, grain size, and optical band gap of Cu₃N:Ag films. Cu₃N:Ag films achieve the most remarkable crystallinity at 0.23 at% of Ag with lattice constant and optical band gap of 0.381 88 nm and 1.30 eV, respectively. Moreover, the doped Ag atoms fill the hollows in the Cu₃N lattice and consequently reach the high-energy defect level. These atoms also generate impurity compound centers at high-energy level, shorten the non-equilibrium carrier lifetime of the films, and weaken the electronic transportation of the films. (paper)