Papers by Author: A. Sólyom

Abstract: Polycrystalline diamond and diamond-like carbon (DLC) films were deposited by microwave chemical vapor deposition (MW-CVD) and by pulsed laser deposition (PLD) respectively. Ar ion bombardment was used to change the properties of these layers. The sp2 bonds were determined directly by reflected electron energy loss spectroscopy (REELS) and further characterization was made by Raman scattering. The polycrystalline diamond showed only very slight π-π* transition at 6.5 eV, but after Ar ion bombardment strong peak was formed but definitely shifted to lower energy compared to the well known π-π* transition of graphite. The as deposited PLD carbon films showed broad peak around 5eV clearly different than the π-π* transition (6.5eV). After Ar+ ion bombardment the peak was shifted also to lower energy range (4-5eV) with a remaining part at 6.5eV. The lower energy part of the peak can be correlated to the transition of sp3 sites, while this change in peak position was not detectable after ion bombardment of the reference HOPG sample, which does not contain sp3 hybridized carbon atoms.

Abstract: Polycrystalline diamond layers are mostly used in various fields of industrial application. Mechanical tension is generated due to the different heat expansion coefficients of the substrate and the layer, which leads to fracturing in some cases. In this work a homogeneous polycrystalline diamond structure has been deposited on Si/SiO2 substrate by microwave assisted CVD method (MW-PECVD). An selective etching technique has been used to remove the silicon below the 2.5 micron thick diamond layer. A self-supporting diamond structure has been created this way. Polycrystalline diamond based heaters and thermometers can be made from doped diamond materials, which can resist corrosive and radiative environment.