Toshiyuki Mihara

Influence of Sputtering and Annealing Conditions on the Structure and Ferroelectric Properties of Pb(Zr,Ti)O3 Thin Films Prepared by RF Magnetron Sputtering

Lead zirconate titanate (PZT) thin films were prepared on Pt/Ti/Corning 7059 glass substrates by RF magnetron sputtering using a Pb(Zr0.5,Ti0.5)O3 ceramic target. X-ray diffraction studies were performed on the films to optimize the sputtering pressure, O2/(Ar+O2) mixing ratio (OMR), annealing temperature and annealing time, to prepare the films in the perovskite phase. As-deposited amorphous film goes through an intermediate pyrochlore phase before crystallizing in the perovskite phase. Perovskite phase formation started at 625°C and annealing at 650°C for 2 h was found to be necessary for complete crystallization in the single perovskite phase. Perovskite phase formation was confirmed with the existence of a perovskite rosette structure by scanning electron micrograph (SEM). Energy dispersive X-ray (EDX) compositional analysis of as-deposited films showed Pb/(Zr+Ti) 1.1; a 10% deviation from the target stoichiometry. Ferroelectric and dielectric properties of the capacitor with thin platinum films as both electrodes were investigated in detail as functions of annealing temperature and annealing time. The marked improvement in the structural and electrical properties observed in the deposited film after annealing was mainly due to the crystal growth of small crystallites. The dielectric constant and loss tangent of the films annealed at 650°C for 2 h were 580 and 0.06, respectively. The films with 1.4 µm thickness that were annealed at 650°C showed a remanent polarization (Pr)=26 µC/cm2 and coercive field (Ec)=51 kV/cm.

Highly conductive transparent F-doped tin oxide films were prepared by photo-CVD and thermal-CVD

Abstract Although high-quality SnO 2 films have been prepared above 400°C, we prepared highly-conductive transparent F-doped SnO 2 films below about 350°C and at high growth rates, using a new raw material system of Sn(CH 3 ) 4 , O 2 containing 5 mol.% O 3 , and HF-acid. At a substrate temperature of 350°C, the films, which had properties such as sheet resistances of 1.6 and 4.5 Ω /□, resistivities of 3.4 and 4.5 × 10 −4 Ω cm, and transmittances including substrates of 70% and 80% at 550 nm, were prepared by thermal-CVD and photo-CVD (chemical vapour deposition), respectively. Several optical and electrical properties of the films prepared by both CVD methods were compared.

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.

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.

High-Deposition-Rate Growth of Lead Titanate Zirconate Films by Reactive Electron Beam Coevaporation

Lead titanate zirconate (PZT) thin films were prepared by reactive coevaporation of lead, zirconium and titanium with an electron beam gun. To promote oxygenation of deposited films, mixed gas of oxygen and ozone was used. A PZT film with a single perovskite phase was obtained at a substrate temperature of 550 o C without post-thermal annealing on a lead titanate film. The deposition rate was 50 nm/min, which was much higher than that in the case of the sputtering method. The axial ratio (c/a) of the tetragonal perovskite phase decreased with the increase of zirconium content

c-Axis Oriented PbTiO 3 Thin Films on MgO and Their Microstructure

PbTiO 3 thin films were prepared on MgO(100) substrates using a conventional rf magnetron sputtering system with a powder target. By optimizing the deposition conditions, highly c-axis oriented PbTiO 3 epitaxial films were obtained. The c-axes of the domains in the films were normal to the substrate, but some a-axes were tilted from the normal towards (100) directions with a particular angle and fourfold symmetry. From the tilt angle and the tilt directions, it is concluded that 90° domain structures were formed by twins, the domain walls of which were (101) twin boundaries.