Reactive DC magnetron sputter deposited copper nitride nano-crystalline thin films: Growth and characterization

CuNx thin films were grown by reactive DC magnetron sputtering and their structural, morphological, optical and electrical properties were evaluated. This study provides insight into the importance of substrate temperature and nitrogen content on the characteristic of CuNx films. Phase analysis and structural properties of these films were identified by X-ray diffraction (XRD) technique. XRD results showed that the CuNx films were single phase and polycrystalline with mixed orientation. Nitrogen excess accommodates in vacant interstitial sites of cubic anti-ReO3 crystal structure of CuNx and exhibits a solid solubility. The variation of surface morphology, studied by scanning electron microscope (SEM), shows suppression of the pyramidal-like grain growth by N richness. Optical study were performed by UV-Vis-near IR transmittance spectroscopy. Film thickness, refractive index and extinction coefficient were extracted from the measured transmittance using a reversed engineering method. Absorption coefficient and electrical resistivity indicate that the CuNx films present extrinsic semiconducting behavior with an indirect optical band gap between 1.19 and 1.44 eV. To confirm the optical band gap energy, a first principle calculation was performed and compared with the measured data. (C) 2012 Published by Elsevier Ltd.