ICMCTF2003 Session B2: Arc and E-Beam Coatings and Technologies

The radially expanding plasma in a Hot Refractory Anode Vacuum Arc (HRAVA) was used to produce metallic coatings. The HRAVA was equipped with a conventional water-cooled metallic cathode, but the anode was made from a non-consumable refractory material. The HRAVA operated initially as a conventional vacuum arc sustained by cathode spot emitted plasma, however at a later stage, the interelectrode region also contained cathodic metal vapor re-evaporated from the hot refractory anode. The re-evaporated cathode material was strongly ionized, creating an anodic plasma without macroparticles (MP's). The HRAVA served as a plasma source with highly reduced MP contamination. In the present work the results of copper thin film deposition with the new device are described.

Arcs were sustained between the parallel end surfaces of a pair of cylindrical electrodes. A copper cathode and thermally isolated molybdenum anode were used. The lateral cathode surface was shielded. Arc currents of 150-250 A were sustained for periods of up to 80 s. The coatings were deposited on 76x26x1mm glass substrates placed at distances of 5.5-16 cm from the electrode axis along the midplane of the inter-electrode gap. In some experiments, the substrate was shielded from the plasma by a shutter, which was opened for a pre-selected time period during the arc. The film thickness was measured using a profilometer, and the coating surface was examined with an optical microscope. The MP's size distribution function was measured.

The observations showed that films with different morphologies formed on the substrate in two regions: facing the anode (anode region) and facing the cathode (cathode region), respectively. The MP content on films deposited by 30 s duration arcs on the anode region was about three orders of magnitude less than on the cathode region. The MP size distribution function in the cathode region was similar to that measured in conventional vacuum arcs. In the anode region a mirror-like film was obtained. The film thickness in the anode region increased linearly with current. The deposition rate in a 200 A arc at the distance 11 cm initially increased linearly with time and saturated after approximately 40 s. The deposition rate for 1 min duration 200 A arc at distance 9 cm was about 0.5 µm/min in the anode region and up to about 2 µm/min in the cathode region.

Ultrathin silver films that are not continuous show relatively high absorption in the visible and low reflection in the infrared. For low-emissivity application on window glass, coalescence of silver islands is crucial for obtaining the desired optical properties of the coating, namely high transparency in the visible and high reflectivity in the infrared. It is well known that the energy of ions arriving at the substrate and the type of underlayer affect nucleation and growth of silver islands. There are a number of studies on nucleation and growth, but little is known about coalescence of silver islands synthesized by more energetic condensation, e.g. filtered cathodic vacuum arc (FCVA). In this work, the effect of underlayer on nucleation and growth of silver films deposited by FCVA was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results are compared with data obtained by magnetron sputtering. Eungsun Byon was supported by the Post-Doctoral Fellowship Program of the Korea Science and Engineering foundation.

This work was supported by the Office of Building Technology, U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

Electron Beam Physical Vapor Deposited (EB-PVD) silicon oxynitride (SiO_xN_y) films of various compositions between SiO₂ and Si₃N₄ were grown by changing the substrate temperature and deposition time The SiO_xN_y films were deposited at various temperatures ranging from 100°C to 400°C on single crystal wafer ( single side polish)and soda lime glass substrates. Films were characterized by using XPS, EDS, Photoluminescence, UV-Visible spectroscopy and Ellipsometry.

The XPS analysis show the incorporation of nitrogen in the films increases with increase in substrate temperature and deposition time.The XPS spectra of the films shows Si,N,O and carbon species on the surface. The incorporation of nitrogen in the films is further confirmed by photoluminescence spectra. The photoluminescence spectroscopy measurements were done at room temperature. The energy of the PL peak for 2.54eV (~490 nm) excitation is 2.30 eV (~560 nm).This is an interesting result since similar spectra has also been observed in porous silicon and silicon oxide implanted with silicon suggesting a likely similar cause for the photoluminescence in all these cases. The annealing effect of SiO_xN_y samples at 800°C on PL intensity is discussed.The ellipsometric measurements shows that the values of refractive indices , n and k are in the range of 1.60 to 1.98 and 0.03 to 0.08 respectively.