Structural, electronic, and mechanical properties of niobium nitride prepared by thermal diffusion in nitrogen

• Published in: Materials chemistry and physics 2013-08, Vol.141 (1), p.393-400
• Main Authors: Ufuktepe, Yüksel, Farha, Ashraf Hassan, Kimura, Shin-ichi, Hajiri, Tetsuya, Karadağ, Faruk, Al Mamun, Md Abdullah, Elmustafa, Abdelmageed A., Myneni, Ganapati, Elsayed-Ali, Hani E.
• Format: Article
• Language: English
• Subjects: Hardness; Nitrides; Thin films; X-ray photo-emission spectroscopy (XPS)
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2013.05.029

Niobium nitride (NbNx) was prepared by heating Nb sample in a nitrogen atmosphere (133 Pa) at a temperature of 900 °C. The structural, electronic, nanomechanical and surface properties of the deposited layers have been determined as a function of processing time. The results suggested that the niobium nitride was crystalline in the single phase of hexagonal β-Nb2N and the nitrogen-to-niobium ratio was found to be in the range of 0.67 ± 0.03 to 0.74 ± 0.03. Longer processing times resulted in layers with higher nitrogen-to-niobium ratios. The mean grain size of these nitrides was about 18 nm. The valence band photoemission and calculated density of state spectra characterized by two peaks were associated with N 2p-Nb 4d hybridization. X-ray photoemission spectra of Nb 3p and 3d core levels revealed a strong interaction with nitrogen along with binding energy shift. As the processing time was increased, the film growth continued with consistent improvement in hardness and modulus. •Hexagonal β-Nb2N was prepared by annealing of Nb sample.•The longer annealing times result in NbNx layers with higher nitrogen-to-niobium ratio.•The hardness values of the films were ranging from 12 to 26 Gpa.