Saburo Kimura

Relationship between crystal structure and chemical composition of PbTiO3 thin films prepared by sputter-assisted plasma CVD

PbTiO3 thin films were prepared by sputter-assisted plasma chemical vapor deposition (CVD) on Pt-coated glass substrates at a substrate temperature of 500°C. As the source materials, a Pb metal target, TiCl4 gas and O2 gas were used. The crystal structures of the films changed from a pyrochlore phase to a perovskite one, and to a PbO (red) one with increasing Pb/Ti atomic ratio.

Laser-damage threshold of Sc2O3/SiO2 high reflector coatings for a laser wavelength of 355 nm

Highly damage-resistant optical coatings are essential for the development of high output energy UV lasers. The authors have prepared Sc2O3/SiO2 high reflector (HR) coatings and measured some of their characteristics (laser-damage threshold for short-pulsed laser of wavelength 355 nm, the effect of a coating layer on the threshold, stress of the coating). The average damage thresholds on fused SiO2, BK-7 and sapphire substrates were 2.9, 3.6 and 3.5 J cm−2 respectively. An SiO2 coating layer improved the threshold by 25%, while an MgF2 layer hardly changed the threshold. When the coating designs were the same, the average damage thresholds of the HR coatings on the BK-7 or sapphire substrate were 20%–25% greater than those on the SiO2 substrate. The (compressive) stress of the HR coating on the SiO2 substrate was 470 kgf cm−2.

Influence of Deposition Parameters on Laser Damage Threshold of 355-nm Scandium Oxide-Magnesium Fluoride High-Reflector Coatings

The experimental results of the laser-induced damage thresholds of Sc2O3/MgF2 high-reflector (HR) coatings for an UV (355-nm, 0.4-ns) pulsed laser have been shown. The deposition parameters have been optimized by use of 5-layer semitransparent coatings, with the distribution of the standing-wave electric-field being similar to that of the HR coatings. For the 5-layer coatings, their threshold values were found to depend on the deposition parameters and the absorption; the coatings with low absorption had high damage threshold. Based on these results, the HR coatings were fabricated on fused silica, BK7 and sapphire substrates, and their thresholds have been measured. The highest average threshold on each substrate have been 3.5, 4.2 and 3.8 J/cm2, respectively.

TfP205. Preparation of lead titanate thin films by reactive electron beam coevaporation using ozone

Abstract Lead titanate(PbTiO3) thin films were prepared by reactive coevaporation of lead and titanium with an electron beam gun. Each of evaporation rates of lead and titanium was independently controlled by each quartz crystal thickness monitor. To promote oxidation of deposited films, a mixed gas of oxygen and ozone was used. When the ratio of lead to titanium was controlled properly, perovskite phase PbTiO3 was obtained at substrate temperature of 550°C without post thermal annealing on glass substrates. The deposition rate was 110nm/min, which was larger than that of prepared by sputtering method and that of prepared by coevaporation without ozone. The ratio of lead to titanium of the perovskite phase films was nearly equal to that of standard PbTiO3 powder sample. The film prepared without post thermal annealing had a smooth surface and was transparent in the visible region.

Preparation of PbTiO3 Thin Films by Sputter Assisted Plasma Chemical Vapor Deposition Method

Lead titanate thin films were prepared by sputter assisted plasma chemical vapor deposition method. Metallic lead as a sputtering target and titanium tetrachloride carried by hydrogen gas were used as lead and titanium sources, respectively. Without post thermal annealing, ferroelectric perovskite phase were obtained at substrate temperature of 550°C on platinum coated glass substrate with the deposition rate of about 70 nm/min. Surface of the film was smoother than the one prepared by post thermal annealing.

Preparation of PLT films by reactive electron beam coevaporation

Abstract Lanthanum modified lead titanate (PLT) thin films were prepared by reactive coevaporation of lead, lanthanum and titanium with an electron beam gun Each of evaporation rates of lead, lanthanum and titanium was independently controlled by each quartz crystal thickness monitor. To promote oxygenation of deposited films, mixture gas of oxygen and ozone was used. A perovskite phase PLT was obtained at substrate temperature of 550°C without post thermal annealing on a glass substrate. Deposition rate was 50nm/min, which was much larger than that of prepared by sputtering method. According to the increase of lanthanum content, axial ratio c/a decreased. The PLT film was more transparent than the PbTiO3 film which was deposited on same conditions.

Substrate dependence of laser-induced damage threshold of scandium oxide high-reflector coatings for UV pulsed laser

The substrate dependence of the laser damage threshold of high-reflector (HR) coatings (Sc2O3/MgF2 HRs and Sc2O3/SiO2 HRs) for a 355-nm pulsed laser was examined. A correlation between the thermal expansion coefficient of the substrates and the damage thresholds was observed: HRs on substrates with larger thermal expansion coefficient (BK-7, sapphire) had higher threshold than those on substrates with a smaller coefficient (fused silica).

Measurement of Laser Damage Threshold of 355-nm Antireflection Coating

The laser damage thresholds of various types of antireflection (AR) coatings for an UV (355-nm) laser system were measured. Among them, the coatings consisting of two low-index materials, SiO2 and MgF2, had the highest average thresholds: 2.1 J/cm2 fused silica substrates and 2.6 J/cm2 sapphire substrates. The SiO2/MgF2 coating is hopeful for UV laser component.

Deceleration of ion beams for film deposition by an electrostatic field

Abstract For the practical use of ion beam deposition (IBD), the deceleration characteristics of Ar+ ion beams of the order of mA and of 10 kV were investigated by using an electrostatic field of a flat deposition electrode. The experiments were carried out by means of measurement of the electrode currents of a deceleration unit settled in an electromagnetic isotope separator and by photographic observation of the ion beams. A preliminary Si deposition was attempted and a metallic film appearance was obtained on an Al2O3 substrate.

Resistance Control of SnO2 Films by Ion Implantation

Transparent-conductive SnO2 films have been prepared by means of ion implantation. An appropriate amount of Antimony atom is implanted into CVD polycrystalline SnO2 films. Using this implantation doping, the sheet resistance of CVD SnO2 films can be controlled precisely at any desirable values. A dose of about 1 × 1016 Sb ions/cm2 brings down the sheet resistivity to such a low value as a commercial goal of 500 Ω/sq, no matter what initial sheet resistivity value is used. A tentative control equation is proposed from the experiment. The Sb atom distribution implanted into the polycrystalline SnO2 film is also investigated by an ion microanalyzer. The peak is a typical amorphus one and the projected range is around 250 A at 60 keV. An annealing at 650 °C does not appreciably affect the distribution of implanted atom.