DC triode sputtering deposition and characterization of N-rich copper nitride thin films: Role of chemical composition

(N-rich) Cu3N polycrystalline films were deposited by DC triode sputtering from a copper target in a mixture of argon and nitrogen atmosphere. Their chemical composition, structure and electrical properties have been studied as a function of deposition parameters: nitrogen partial pressure (PN2PN2) and DC bias. Depending on PN2PN2 and DC bias, the atomic nitrogen incorporated into the layers ranges from 26 at% to a limit value of 33 at% as measured by ion beam analysis (IBA) techniques. X-ray diffraction (XRD) data show that most of the layers are single phase, polycrystalline and with preferential 〈1 0 0〉 orientation. Optical and electrical measurements indicate that all layers present intrinsic semiconductor behavior with a thermal gap around 0.21–0.25 eV and a direct optical gap between 1.5 and 1.7 eV. The physical properties observed for these films are discussed in relation to nitrogen contents and sputtering parameters.