A Raman-scattering study on the interface structure of nanolayered TiAlN∕TiN and TiN∕NbN multilayer thin films grown by reactive dc magnetron sputtering

Nanolayered multilayer coatings of TiAlN∕TiN and TiN∕NbN were deposited on Si (100) substrates at various modulation wavelengths (i.e., bilayer thickness, Λ) using a reactive dc magnetron sputtering system. These coatings were characterized using micro-Raman spectroscopy to study the effect of interfaces on the optical-phonon modes. For TiAlN∕TiN multilayers, the optical-phonon band shifts to higher frequencies with a decrease in the modulation wavelength. Furthermore, the optical-phonon band shifts to higher frequencies with an increase in the substrate temperature for TiAlN∕TiN multilayers deposited at Λ=80A. No such shift was observed for single-layer TiN and TiN∕NbN multilayer coatings. This observed shift has been attributed to interdiffusion between the layers during deposition, which is more for TiAlN∕TiN multilayers as compared to TiN∕NbN multilayers. The x-ray-diffraction data showed well-defined satellite reflections for TiN∕NbN multilayers at low modulation wavelengths and very weak satellite r...