Shoichi Mochizuki

Preparation of Pb(Zr,Ti)O3 thin films by RF-magnetron sputtering with single stoichiometric target: structural and electrical properties

Abstract Polycrystalline and ferroelectric Pb(Zr,Ti)O 3 films were prepared by RF-magnetron sputtering. No excess lead was used either during sputtering or during post-deposition annealing. The structural, microstructural, and electrical properties were examined as function of annealing treatments and bottom platinum electrode thickness. Surface morphology and compositional analysis were done with scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The lattice constant of the film crystallized in the perovskite phase was 4.09 A. Relative dielectric constants of Pb(Zr,Ti)O 3 films grown on 0.3 and 1 μm thick platinum were 990 and 942, respectively, and much difference has not been observed in the loss tangent value. Remanent polarization and coercive field of the Pb(Zr,Ti)O 3 films grown on 0.3 μm thick platinum coated glass were 22 μC/cm 2 and 59 kV/cm, respectively, where as that on 1 μm thick platinum were 26 μC/cm 2 and 51 kV/cm.

Preparation of ferroelectric Pb(Zr0.5,Ti0.5)O3 thin films by sol–gel process: dielectric and ferroelectric properties

Abstract Ferroelectric lead zirconium titanate (Pb(Z 0.5 ,Ti 0.5 )O 3 ) thin films were prepared by sol–gel spin coating technique. Three-step pre-annealing heat treatment was employed to prepare crack-free films. Phase-pure perovskite crystallization was obtained by annealing the films on Pt/Ti/Corning 7059 glass substrates at 550 °C. Films were having fine-grained microstructure with average grain size of the order of 20 nm. Resistivity of the 0.54-μm-thick film was the order of 10 10 Ω cm at 15 V. Dielectric constant and loss tangent at 10 kHz were in the range 1000–1250 and 0.04–0.077, respectively. Remanent polarization ( P r ) and coercive field ( E c ) were in the range 26–29 μC/cm 2 and 49–58 kV/cm, respectively.

Perovskite crystallization of sol-gel processed (Pb, La0.06, Gd0.02)(Zr0.65, Ti0.35)O3 thin films: Dielectric, ferroelectric and optical properties

Ferroelectric lead lanthanum gadolinium zirconium titanate (PLGZT) thin films were prepared by the sol-gel spin coating technique. Three-step preannealing heat treatment was employed to prepare crack-free films. Various types of substrates, and the effects of the seed layer and annealing temperature on the perovskite crystallization were studied. Phase-pure perovskite crystallization was obtained by annealing the films on PbTiO 3 /Pt/Ti/Si substrates at 700 °C for 30 min. The Auger electron spectroscopy depth profile showed uniform elemental distribution along the thickness except the surface and interface regions. Dielectric constant and loss tangent at 10 kHz were 1000 and 0.06, respectively. Remanent polarization (P r ) and coercive field (E c ) were 11.8 μC/cm 2 and 71 kV/cm, respectively. The direct band gap energy was 3.55 eV for the amorphous films. The refractive index and extinction coefficient at 610 nm for amorphous PLGZT films were 2.14 and 0.0028, respectively. The dispersion of the refractive index was interpreted in terms of a single electronic oscillator at 6.06 eV.

Electrochromism in nickel oxide films prepared by plasma oxidation of nickel-carbon composite films

Abstract We report on a novel dry process for preparing NiO films by plasma oxidation of NiC composite films, which have been deposited by co-evaporation of Ni and C from two different sources. After being hydrated in KOH electrolyte, the NiO films show fast response and good cycling ability.

AUGER ANALYSYS OF PBTIO3 FILMS PREPARED BY REACTIVE ELECTRON BEAM COEVAPORATION

Abstract Auger electron spectroscopy was applied to study depth profiles of PbTiO3 thin films which were prepared by coevaporation with high deposition rate of 50 nm/min and with substrate temperature of 550°C. When the films were deposited on sputtered Pt films, Pb was concentrated on the Pt surface and PbPtxwas formed. On the contrary, a perovskite phase of PbTiO3 was obtained without post thermal annealing on a sputtered 1% Te-added indium tin oxide (S-ITO) substrate. Chemical composition of the film on S-ITO was not dependent on depth excepting surface region.

C-axis-oriented PbTiO3 thin films prepared by sputter-assisted plasma CVD

Abstract c-axis-oriented PbTiO3 thin films were grown by sputter-assisted plasma CVD on MgO(100) and on Pt(100)/MgO( 100). Highly c-axis-oriented PbTiO3 thin films on both MgO(100) and Pt(100)/MgO(100) had 90° domains in the c-axis-oriented region but had none in the a-axis-oriented region. Lower c-axis-oriented samples had no 90° domains in a- and c-axis-oriented regions on both MgO(100) and Pt(100)/MgO(100) substrates. The higher the c-axis orientation, the larger was the tilt angle between the a-axis of 90° domain in the c-axis-oriented region and the normal to the substrate. This indicates that the axial ratio, c/a, is affected by the c-axis orientation.

Effects of PbTiO 3 Seed Layer on the Characteristics of RF-Sputtered Pb(Zr 0.5 ,Ti 0.5 )O 3 Thin Films

The effects of seed layers on the characteristics of rf-sputtered lead zirconium titanate thin films were investigated. Prior to sputtering, PbTiO 3 seed layers (100 nm) were deposited onto the Pt/Ti/Si and Pt/Si substrates by sol-gel (spin coating) processing method. Structure-property relation was studied as functions of substrate temperature and sputtering conditions. Special efforts were given in optimizing the deposition parameters to prepare the films in the perovskite phase without post deposition annealing. Dielectric constant and loss tangent of the films were in the range 800-950 and 0.04 -0.06, respectively. Remanent polarization and coercive field were 23.1 w C/cm 2 and 75kV/cm, respectively, for the films without PbTiO 3 seed layer, where as the corresponding quantities for in situ -deposited perovskite Pb(Zr, Ti)O 3 films on PbTiO 3 seed layer were 28 w C/cm 2 and 65 kV/cm, respectively.

Preparation of PbTiO3 films on conductive oxide by reactive electron beam coevaporation

Abstract PbTiO3 thin films were prepared on conductive oxide substrates by coevaporation of lead and titanium. When PbTiO3 was deposited on a sputtered Pt film, the chemical composition of deposited film was changed (Pb deficient) and the crystal structure was that of PbPtx. On the contrary, a perovskite phase of PbTiO3 was obtained without post thermal annealing on a sputtered 1% Te-added indium tin oxide substrate. The substrate temperature was 550°C and the deposition rate was greater than 50 nm/min, which was much larger than that by the sputtering method.

Fabrication and evaluation of active spectral filter with metal-insulator-metal structure for visible light communication

Plasmonic spectral filter based on a metal-insulator-metal (MIM) structure is one of the candidates of active devices with white LEDs in the ubiquitous network society. In order to make this filter electrically active, “silver alloy and quartz-coated silver films” and “PLZT films by the dry and wet processes” were fabricated and evaluated under high annealing temperatures. The quartz-coated silver film and the PLZT film by the dry process” could be possible as the metal and insulator layers, respectively. The issue of thickness determination of the insulator layer is also discussed.

Influence of Deposition Rate and Intermediate Layer on Crystal Structure of Pb(Zr,Ti)O 3 Thin Films Prepared by RF Sputtering

Pb(Zr,Ti)O 3 (PZT) thin films were prepared by rf magnetron sputtering. To obtain perovskite phase at low substrate temperature, the influence of intermediate layers on crystallization were investigated. Mixed phases of perovskite and pyrochlore PZT were obtained on PbTiO 3 intermediate layer at substrate temperature of 610°C. On the contrary, perovskite phase PZT was obtained without post deposition thermal annealing on amorphous PZT intermediate layer at substrate temperature and deposition rate of 610°C and 6 nm/min, respectively. In PZT (except the surface region) and in amorphous PZT intermediate layer, chemical composition of auger depth profile was uniform.