Oxidation behavior of copper nitride thin films deposited by direct current magnetron sputtering

The oxidation characteristics of copper nitride (CuxN) thin films deposited by dc magnetron sputtering in optimized sputtering conditions at room temperature and different substrate temperatures and those annealed at various temperatures under vacuum, nitrogen, oxygen and air atmospheres, and on exposure to laser radiation were investigated. Optical transmittance spectroscopy, sheet resistance measurements performed in in-vacuo and ex-vacuo conditions, Raman spectroscopy, and x-ray diffraction measurements were used to monitor the oxidation and also the decomposition characteristics of the films. The films exhibited high susceptibility to oxidation in the presence of oxygen even in residual level, large humidity effect on oxidation, and ambient dependent decomposition behavior. The oxidation pattern of the films was found to be defined by their initial composition. The oxidation of CuxN composition starts from Cu2O phase and progresses to CuO phase, whereas the Cu-rich composition stabilizes in Cu2O phase. The present study establishes the ambient and substrate / annealing temperature-dependent oxidation and decomposition behavior of the CuxN films and demonstrates the possibility of controlling their extent by adjusting these deposition and post-deposition parameters. These findings are important for fundamental understanding and relevant for resistive switching, optical storage, and photo-catalysis applications of the CuxN films.