Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment

Thin film structures own significantly different properties than the bulk material and consequently they found applications in various fields of modern nanotechnology. In the past few decades, special attention was paid to research in the field of ion beams modification of thin films. Among the techniques ion implantation is particularly emphasized, as a method that allows the incorporation of impurity atoms in the material with the possibility of precise control of process parameters. As non-equilibrium technique (not controlled by diffusion laws), ion implantation enables production of a new materials, that can not be produced with other conventional methods. The main objective of this research was to gain new fundamental knowledge in the field of modification of thin film/Si systems induced by ion irradiation. The present work consists of two parts. In the first part of the experiment the changes induced by ion implantation inside of the thin layer were examined – effects of different ionic species on the microstructure, optical and electrical properties of chromium nitride (CrN) were investigated. The second part of the experiment refers to the examination of changes at the thin film/substrate interface due to ion implantation – the influence of ion bombardment on the ion beam mixing of Co/Si system was investigated as well as formation of cobalt-silicides during the process of ion irradiation and./.or annealing of the samples. Rutherford backscattering spectrometry (RBS) was used to obtain concentration depth profiles of elements and to determine the stoichiometry of the layers. Structural and phase analyses of the systems were performed by X-ray diffraction (XRD), transmission electron microscopy combined with selected area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis together with fast Fourier transformations (HRTEM/FFT). Optical properties of modified CrN layers were determined using infrared spectroscopy (IR) and electrical resistivity was measured using four point probe method. CrN thin films (thickness of ~280 nm) were deposited by reactive sputtering on crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV V+ ions. In the case of Ar+ ions the samples were implanted in the range of 5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of 1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all ions are stopped inside the layer, to avoid any atomic mixing and pos