| AVS 64th International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Monday Sessions |
| Session EL+AS+EM+TF-MoM |
| Session: | Application of SE for the Characterization of Thin Films and Nanostructures |
| Presenter: | Jiri Bulir, Institute of Physics ASCR, Czech Republic |
| Authors: | J. Bulir, Institute of Physics ASCR, Czech Republic J. More Chevalier, Institute of Physics ASCR, Czech Republic L. Fekete, Institute of Physics ASCR, Czech Republic J. Remiasova, Institute of Physics ASCR, Czech Republic M. Vondracek, Institute of Physics ASCR, Czech Republic M. Novotny, Institute of Physics ASCR, Czech Republic J. Lancok, Institute of Physics ASCR, Czech Republic |
| Correspondent: | Click to Email |
The plasmonic applications requires search for novel materials with metal-like optical properties and low optical losses. Transition metal nitrides such as TiN, TaN, ZrN, HfN, NbN exhibit metallic properties depending on concentration of free-carrier of charge. Their plasmonic properties can be tuned by deposition parameters controlling the film structure and the stechiometry.
In this work, we deal with study of growth process of TiN films. The films are grown by RF magnetron sputtering on fused silica, silicon and MgO substrates at substrate temperature ranging from 20°C to 600°C. The growth process is monitored using in-situ spectral ellipsometer in spectral range from 245 to 1690 nm. The ellipsometric data, which are obtained during the deposition process, are attentively analysed using mathematical models based on Drude-Lorentz oscillators.
The Lorentz oscillators are used for description of interband transition in ultraviolet and visible spectral range, whereas the Drude oscillator describes the free-electron behavior in the infrared spectral range. We show that the free-electron behavior is affected by thickness of the ultrathin coatings due to electron scattering effects at the interfaces. Number of physical parameters such as free-electron concentration, Drude relaxation time and electrical conductivity is estimated at each stage of the deposition process by analysis of dielectric functions using the mentioned model. The resulting evolution of the electrotransport properties during the TiN film growth is presented. Special attention is devoted to the initial nucleation stage when the free-electron behaviour is significantly influenced by the interface between the substrate and the TiN film. Based on evolution of electrotransport properties, we discuss differences between polycrystalline growth of TiN film on Si and fused silica substrates and epitaxial growth on MgO substrates.
The accomplished TiN coatings are analyzed using infrared ellipsometer operating in spectral range from 1.7μm to 30μm where the optical constants are infuenced most importantly by free-electron behaviour. The obtained results are compared with those obtained by the in-situ ellipsometer. Special attention is focused on scattering of free electrons at grain boundaries and at the TiN layer interfaces. The estimated parameters are correlated with structure changes such as grain coarsening and surface morphology. The crystallinity is analysed by X-ray Difractometry. The surface morphology of the completed coatings is studied using Atomic Force Microscopy and Scanning Electron Microscopy. The TiN film stechiometry is estimated by X-ray Photoemission Spectroscopy.