Analysis of Ti nanolayers irradiated with Xeq＋ ions using synchrotron radiation based X-ray reflectometry

Abstract

To characterize morphology and physicochemical properties of nanolayers the surface-sensitive X-ray spectroscopy techniques are often successfully applied. These techniques are still being developed in order to achieve better depth resolution and detection limits. In this article, we present measurements of morphology of Ti nanolayers (deposited on Si substrate) with thickness of 25 nm, 50 nm and 75 nm, unmodified and irradiated with Xeq＋ ions (where q is the charge state of the ion), which were carried out using synchrotron radiation (SR) based XRR technique. The nanolayers were irradiated with low-energy (of the order of hundreds of keV) highly charged Xeq＋ (q = 25, 30, 35) ions, at the Kielce EBIS facility (Jan Kochanowski University, Kielce, Poland). The SR-XRR measurements were performed at Elettra Synchrotron X-ray fluorescence beamline, using X-ray beam with energy of 6.0 keV. The obtained reflectivity curves were modelled by creating a structure consisting (from the bottom to the top) of silicon substrate (Si), main Ti layer, TiO2 layer, and TiO2(a) amorphous layer, with contamination of hydrocarbons, carboxylates or alkoxides. The experimental results obtained with the SR-XRR technique for the nanolayers, unmodified and irradiated with the Xeq＋, show the dependence of the TiO2 layers morphology on the Xe ions charge state. In the article the sample preparation, measurement using SR-XRR and the data analysis procedures are described in details and the advantages and disadvantages of the SR-XRR technique in the context of nanolayer studies are discussed.