Superconducting niobium nitride thin films by reactive pulsed laser deposition

• Published in: Thin solid films 2013-10, Vol.545, p.601-607
• Main Authors: Ufuktepe, Y., Farha, A.H., Kimura, S.I., Hajiri, T., Imura, K., Mamun, M.A., Karadag, F., Elmustafa, A.A., Elsayed-Ali, H.E.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Hardness; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nanostructure; NbN; Niobium nitride; Physics; Pulsed laser deposition; Structure and morphology; thickness; Superconductivity; Surface and interface electron states; Surface states, band structure, electron density of states; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; Transition temperature variations; X-ray spectroscopy
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.08.051

The structural, electronic, and nanomechanical properties of cubic niobium nitride thin films were investigated. The films were deposited on Si(100) under different background nitrogen gas pressures (26.7-66.7Pa) at constant substrate temperature of 800°C by reactive pulsed laser deposition. Our results reveal that the NbNx films exhibit a cubic δ-NbN with strong (111) orientation and highly-oriented textured structures. We find nitrogen background pressure to be an important factor in determining the structure of the NbNx films. The dependence of the electronic structure as well as that of the superconducting transition temperature (Tc) on the nitrogen gas background pressure is studied. A correlation between surface morphology, electronic and superconducting properties is found for the deposited NbNx thin films. The highly-textured δ-NbN films have a Tc up to 15.07K. Nanoindentation with continuous stiffness method is used to evaluate the hardness and modulus of the NbNx thin films as a function of depth. The film deposited at nitrogen background pressure of 66.7Pa exhibits improved superconducting properties and shows higher hardness values as compared to films deposited at lower nitrogen pressures. •NbN thin films were deposited on Si(100) using reactive pulse laser deposition.•Different nitrogen background pressures were used.•Increasing nitrogen gas pressure impacts the phase and superconducting properties.•Thin NbN films with superconducting phase showed transition temperature up to 15.07K.