Silicon and zinc were doped to cubic boron nitride (cBN) thin films by sputtering bulk dopant sources during the film deposition. Concentrations of these two elements showed different in-plane distributions, presumably caused by the difference of the sticking probability on the growing surface. Silicon impurity did not behave as an active dopant in cBN. However, zinc doping enhanced the electric conductivity from 10−8 to 10−2 (Ω−1cm−1) as the zinc concentration increased from undoped to approximately 2 %.

Nanostructured and thick SiC coatings have been successfully deposited on Si and graphite substrates by thermal plasma physical vapor deposition (TPPVD) using ultrafine SiC powder as a starting material. The control of processing parameters such as substrate temperature, composition of plasma gases, permits to the deposition of SiC coatings with a variety of microstructures and with various morphologies from dense to columnar. The maximum deposition rate reached 200 nm/s. Seebeck coefficient up to −480 μV/K was obtained for the non-doped coatings with stoichiometric composition. Nitrogen doping to the coatings made it possible to decrease the electrical resistivity from 10-2∼10-3 to 10-4∼10-5 Ωm and showing the maximum power factor of 1.0×10-3 Wm-1K-2 at 973 K.

Deformation behavior of the BN film was dynamically observed by high-resolution transmission electron microscopy. BN thin films were deposited on a narrow edge of Si flakes, using inductively coupled plasma-enhanced chemical vapor deposition. High-resolution observation of the sample revealed that the BN film was possibly deposited on the edge of the Si thinned to less than 10 nm in thickness, whose morphology varied depending on the thickness of the Si edge. Intriguing mechanical properties of the BN films, especially relating their dynamic behavior, were clearly verified by the high-resolution observation with piezo-ceramic tube for three-axis positioning of an indenter.

Cubic boron nitride (cBN) thin films were deposited on silicon wafers by low-pressure inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD). By using special substrate pre-treatment processes including positive biasing treatment in H2 plasma or 1200 K pre-heating in H2 atmosphere followed by an N2 plasma treatment, turbostratic BN (tBN) intermediate layer was revealed to directly grow on Si substrates without an initial amorphous layer. The thickness of the tBN transition layer can be reduced to less than 3 nm.

This research is the first attempt at applying thermal plasma chemical vapor deposition (TPCVD) for the ultrafast deposition of Si films for solar cells. A conventional deposition process of Si films, such as plasma-enhanced chemical vapor deposition (PECVD), is capable of a maximum deposition rate of approximately 5 Å/s and it takes a relatively long time to deposit an intrinsic layer. In this paper we report a novel ultrafast deposition approach using dc-rf hybrid TPCVD. The extreme improvement of stability, controllability, and cleanliness of the process enabled the deposition of microcrystalline Si films at the ultrafast rate of over 1000 nm/s, which is about 2000 times faster than that by conventional CVD. Moreover, a minimum defect density of 7.2×1016 cm−3was achieved by post-treatment of the film in 2 Torr H2/Ar plasma. Monte-Carlo simulation and step coverage analysis suggested that the precursor is an approximately 1 nm cluster with a sticking probability of about 0.6. The success of this research will lead to the development of commercially viable technology in a roll-to-roll system in the near future, and will fundamentally change the established concepts of Si deposition technology.

In the manufacture of solid-oxide fuel cells (SOFCs), thermal-plasma technology, especially plasma spraying, offers several advantages, the most important of which is the ability to achieve considerably higher deposition rates than those that can be obtained with such approaches as physical or chemical vapor deposition (PVD or CVD). This article describes an international collaborative research project partially funded by NEDO (New Energy and Industrial Technology Development Organization, Japan) and carried out at five research laboratories around the world: at the University of Tokyo and National Institute for Research in Inorganic Materials (NIRIM) in Japan, the University of Minnesota in the United States, the University of Sherbrooke in Canada, and DLR—Stuttgart in Germany. The objective of the project was to conduct a comparative study on the possible use of four thermal-plasma spraying techniques for the integrated fabrication of SOFCs.