Hironori Fujisawa

Effects of the utilization of a buffer layer on the growth of Pb(Zr, Ti)O3 thin films by metalorganic chemical vapor deposition

Abstract Metalorganic chemical vapor deposition (MOCVD) growth of Pb(Zr,Ti)O3 (PZT) thin films employing a two-step growth process was investigated. In the two-step growth process, the effects of the utilization of a PbTiO3 buffer layer on the succeeding growth of PZT thin films were observed. The orientation of the PZT thin films was controlled by changing the orientation of the PbTiO3 buffer layer deposited on the substrate. The degree of orientation of PZT was also influenced by the use of a PbTiO3 buffer layer. From atomic force microscope (AFM) observations, it was found that the main growth mechanism of (111)-oriented PbTiO3 was two-dimensional growth and that the PbTiO3 buffer layer played an important role as dense nuclei in the succeeding PZT growth.

Effects of La and Nb modification on the electrical properties of Pb(Zr, Ti)O3 thin films by MOCVD

Abstract PLZT and PZTN thin films were successfully grown by MOCVD. The effects of La and Nb modification on the electrical properties were investigated. The Pr, Ec and current densities of the PLZT and PZTN films decreased as the La and Nb contents increased. An improvement in switching fatigue by the modification of La and Nb was observed. However PLZT and PZTN films also showed smaller switching charge densities than those of non-doped PZT films.

MOCVD of ferroelectric PLZT thin films and their properties

Abstract MOCVD of PLZT thin films was performed. Highly oriented PLZT thin films were obtained at a substrate temperature of 620°C. The effects of the La content on the electrical properties of the PLZT thin films were investigated. The remanent polarization and coercive field of the PLZT films decreased with an increase in the La content. A decrease in the leakage current densities caused by La doping was observed. With respect to the current-time characteristics, the PLZT films did not show a steady state condition up to 103 seconds. The possibility of using La(i-C3H7C5H4)4 as a new La precursor was also discussed.

Characterization of Pb(Zr,Ti)O3 thin films by MOCVD using the total reflection X-ray diffraction method

Abstract PZT thin film of 250nm thickness was prepared on Pt/MgO(100) by metal-organic chemical vapor deposition(MOCVD). The vertical structure of PZT was evaluated using θ-2θ XRD method. The “in-plane” structure and orientation relationship between PZT, Pt and MgO was evaluated using energy-dispersive typed total reflection X-ray diffraction method.

Nanoscale Investigation of MOCVD- Pb(Zr,Ti)O3 Thin Films Using Scanning Probe Microscopy

Applications of SPM (scanning probe microscopy) techniques for nanoscale investigation of ferroelectric Pb(Zr,Ti)O3 (PZT) thin films are described. Topics are (1) local current flow in polycrystalline Pb(Zr,Ti)O3 (PZT) thin films, (2) ferroelectric properties of nanosized PZT islands and (3) polarization switching processes in epitaxial PZT thin films and capacitors. They are investigated using atomic force microscopy (AFM), transmission electron microscopy (TEM), conductive AFM and piezoresponse scanning force microscopy (PFM).

Properties of ferroelectric (Pb,La) (Zr,Ti)O3 thin films by MOCVD

Abstract (Pb,La)TiO3 (PLT) and (Pb,La)(Zr,Ti)O3 (PLZT) thin films were successfully grown by MOCVD, using (C2H5)3PbOCH2C(CH3)3, La(dpm)3, Zr(O-t-C4H9)4 and Ti(O-t-C3H7)4 as precursors. The PLT and PLZT thin films showed good dielectric and ferroelectric properties. PLZT films showed better fatigue properties than PZT films. Large area growth of PLZT thin films on a 6 inch silicon wafer was carried out and uniform PLZT films with a variation in film thickness of ±1.5% could be obtained. The case of La(i-C3H7C5H4)3 as a new La precursor for growing PLT and PLZT will be discussed.

Photo-enhanced MOCVD of Pb(Zr,Ti)O3 thin films using O3

Effects of O3 on the growth and electrical properties of Pb(Zr,Ti)O3 (PZT) thin films grown by photoenhanced metalorganic chemical vapor deposition (MOCVD) were investigated. Ferroelectric PZT films were obtained by both MOCVD and photoenhanced MOCVD using (3 at substrate temperatures higher than 560 degree(s)C. The crystalline orientation, growth rate and growth temperature were scarcely influenced by the use of O3 and photoirradiation. However, in the leakage current characteristics, an improvement in breakdown voltage by the use of O3 and photoirradiation was observed. From SEM observations, it was found that this improvement may be caused by the microscopic change in film structure.