Jaanus Eskusson

Er:YAG thin films and nanocrystals prepared by pulsed laser deposition

Thin films of erbium-doped YAG (Y3Al5O12) were grown by pulsed laser deposition, followed by high temperature (>1100 degree(s)C) post-annealing. The deposition was carried out on MgO and MgAl2O4 substrates in ultra-high vacuum chamber with KrF excimer laser at fluences 2.5-3 J/cm2. Influence of growth conditions (substrate temperature, gas environment, annealing temperature) on structural, topographical, and optical properties was investigated by using optical spectroscopy, X-ray diffraction, and atomic force microscopy.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Surface analysis of supercapacitor electrodes after long-lasting constant current tests

FIB-SEM, XPS, TOF-SIMS and electrochemical methods have been used for the characterisation of physical properties and chemical composition of microporous carbide derived carbon electrodes, prepared from TiC at 950 °C (noted as TiC-CDC) after 40000 charge/discharge cycles. Changes in surface chemical composition of TiC-CDC electrodes, includes partial contamination with reaction intermediates (F2, CHO-, CN-, organic radicals), and Al current collectors, like partial dissolution of Al from positively charged electrode and deposition of Al onto the negatively charged TiC-CDC electrode surface, have been analysed.

Synthesis of diamond-like carbon films by pulsed laser deposition in a tiny vacuum chamber

Diamond like-carbon films were fabricated by pulsed laser ablation of a liquid target (vacuum oil) in a very small (volume below 1 cm3) vacuum chamber, where the film was deposited onto the inner surface of the chamber window. The synthesis was carried out at room temperature using 248 nm KrF excimer laser. The sp3 hybridization carbon formation was additionally promoted by gaseous H2O2 flow through the reaction chamber. Deposited diamond-like carbon films were characterized by Raman scattering spectroscopy, optical and atomic force microscopy. The results indicated that higher sp3 content was present in the film areas exposed to the laser irradiation during the deposition. The surface roughness of these areas was lower compared with that of the non-irradiated areas. Optical microscopy observations indicated that the films had interference-colored regions on laser irradiated areas. These colored regions were significantly different from their surroundings, which were grey or brown. Thus, the interferencecolored regions have very wide band gap (&Dgr;E > 3 eV) and accordingly, high sp3 hybridized carbon content.