Surface oxidation of copper nitride (Cu3N) has been a major obstacle to its practical applications, such as resistive switching, thermoelectrics, and optoelectronics, despite its unique semiconducting properties. This article investigates the influence of working pressure on the structural properties of sputtered Cu3N thin films and explores the role of surface oxidation on their electrical properties. X-ray diffraction (XRD) analysis confirms the formation of phase-pure cubic Cu3N with a transformation in the preferred orientation with a working pressure more than 3 Pa. Raman spectroscopy reveals the presence of copper oxide phases, which were not observed in XRD. These oxide phases are primarily confined to the surface, as confirmed by depth-profiled XPS core spectra. The surface oxidation directly influences electrical transport properties by modifying both carrier concentration and mobility, supported by stability studies under ambient conditions. These results suggest that working pressure plays a crucial role in achieving stoichiometric Cu3N films and stabilizing their electrical transport properties by limiting surface oxidation, making them suitable for resistive switching and thermoelectric applications under ambient conditions.
Madhu et al. (Mon,) studied this question.