Hideki Kokai

Change in photoluminescence from Er-doped TiO2 thin films induced by optically assisted reduction

Erbium-doped TiO2 (TiO2:Er) thin films with the anatase structure have been prepared on Si substrate by laser ablation. Sharp and intense Er-related emission in the visible region as well as in the IR region has been observed under over-band-gap excitation. The broad photoluminescence (PL) peaking at about 530 nm newly appears at low temperature. It has been understood that the broad PL is induced by an optically assisted reduction effect that is caused by both the H2O adsorption and the reduction process of TiO2 to Ti2O3 by UV illumination. In the IR region, Er-related emission consisted of one main peak located at 1.534 μm and many subpeaks located at around 1.54 μm can be observed even at room temperature. The drastic thermal quenching of the Er-related 1.54 μm emission is also considered due to the optically assisted reduction effect.

Oxygenation Process of Ti–O Films Formed by Reactive Ion Plating

Ti–O films were deposited under various conditions by RF reactive ion plating. The structures of the TiO2 films were controlled using various parameters such as substrate temperature, RF power, deposition rate, and pressure of reactive gas. By changing the deposition rate at the substrate temperature of 250°C, the crystal structure could be changed from an anatase phase to a rutile phase. In other words, a rutile structure could be deposited even at a low substrate temperature. The emission spectra of ions and excited species in the plasma were measured by optical emission spectroscopy (OES). Relative spectral intensities of these species were studied. The resulting relative relationship of emission intensities of Ti* and O2+ was found to influence reactions in Ti–O film formation.

Large-area electron cyclotron resonance plasma source with permanent magnets

A large-area electron cyclotron resonance (ECR) plasma is generated by using permanent magnets and applying the whistler-mode launching of microwaves. A uniform plasma is produced with the uniformity of ±3.5% over 20 cm and ±1.8% over 16 cm in diameter; the plasma space potential is about 17 V with the uniformity of ±1% over 20 cm. The maximum ion current density is about 11.5 mAcm-2. The purity of the produced plasma is high. No damage was found after the operation for 100 h with the microwave power of 600 W.

Zinc-Oxide Film Synthesized by ECR Oxygen Plasma

ZnO films were deposited using an evaporation system with an oxygen ECR plasma. The ECR plasma was produced in an octapole magnetic field with 2.45 GHz microwave. The deposited ZnO films, which have 3.3 eV band gap, were obtamed without heating (55°C). Deposition was carried out on substrates set in two regions to examine the effect of ion irradiation; one region was in the octapole field (ion rich atmosphere) and the other was the area outside of it (ion poor atmosphere). The deposition in the ion poor atmosphere gave high quality films. The film structure was analyzed by means of optical spectrophotometer, RHEED, SEM and X-ray diffraction.

High-power microwave window for reactive plasma production

It is experimentally shown that a high-power coaxial microwave window, the surface of which is covered with a Cr2O3 thin film, is very stable against reactive plasma irradiation.

Surface modification of uhv wall by a combination of magnetron sputtering of chromium and oxygen plasma

Abstract A chromium oxide film is deposited on a stainless steel sheet by means of a combination of magnetron sputtering of chromium with an oxygen-argon mixture plasma. The structure of the film and the characteristics of hydrogen permeation through the film are investigated. The corking effect of the oxide film is experimentally evident.

SURFACE MODIFICATION OF UHV WALL BY PLASMA CHEMICAL METHOD

Chromium oxide thin film was deposited on the inner wall surface of a stainless steel pipe by means of magnetron sputtering under the existence of an oxygen plasma. From the xps observation the film was identified to be Cr2O3. Comparison of outgassing characteristics between the pipe coated by chromium oxide film and that without the film was conducted after discharge cleaning by an ECR hydrogen plasma. The existence of Cr2O3 film shows a low outgassing rate and possibility to be an obstacle against hydrogen atom transportation.

Observation of a Visible Line Emission from RF and ECR Oxygen Plasmas

Spatial distributions of 777-nm (3s5S-3p5P) emission from oxygen ECR (2.45 GHz) and RF (13.56 MHz) plasmas are observed near an electrode. For the ECR plasma, a peak in the emission near the resonance zone was observed under a certain pressure (4 × 10-3 Torr) accompanied by a decrease in the emission toward the electrode. For the RF plasma, an increase in the emission toward the electrode was observed.

Protection of Organic Materials Against Ultraviolet Rays by Ion-Plated Zinc-Oxide Layer

When organic insulating material is used in open air, the damage caused by ultraviolet irradiation becomes an essential problem. It is necessary to protect the material by a surface coating film having opacity in the ultraviolet region. In this study, cycloaliphatic epoxy resin and quartz substrates were coated with zinc oxide films by the ion plating method. The samples were irradiated by ultraviolet rays from a high-pressure mercury-vapor lamp with an intensity 14 times stronger than in the natural condition. The toughness and effectiveness of the protective film was proved by the estimation of its electric resistance change.

Decarbonization by using ECR plasma

Decarbonization rates were measured by the use of ECR plasmas of H2 or O2. The rates are 2.0×1016 m-2s-1 for H2 and 2.4×1018 m-2s-1 for O2 at the same pressure of 1.6×10-2 Pa. The rate for O2 is two orders of magnitude higher than that for H2. These results are analyzed depending on the equilibrium theory and the processing of decarbonization can be explained.