T. Yu

Enhanced fatigue and retention properties of Pb(Ta0.05Zr0.48Ti0.47)O3 films using La0.25Sr0.75CoO3 top and bottom electrodes

Ferroelectric perovskite Pb(Ta0.05Zr0.48Ti0.47)O3 thin-film capacitors having LaxSr1−xCoO3 bottom and top electrodes have been prepared on Pt/TiO2/SiO2/Si(001) substrates by pulsed-laser deposition. It is found that La0.25Sr0.75CoO3 bottom electrodes with cubic structure strongly promote the formation of (001) texture of PTZT films and improve the fatigue and retention properties of the capacitors. The polarization of the La0.25Sr0.75CoO3/Pb(Ta0.05Zr0.48Ti0.47)O3/La0.25Sr0.75CoO3 capacitors with a Pb(Ta0.05Zr0.48Ti0.47)O3 thickness of 400 nm were subjected to no degradation after 1×1010 switching cycles at an applied voltage 5 V with a frequency of 1 MHz. The capacitor retains more than 92.6% of its polarization after a retention time up to 105 s. The possible microstructural background responsible for the excellent fatigue and retention properties was discussed.

The c-axis length and phase transition temperature change in an epitaxial PbTiO3 thin film grown on a SrTiO3(001) substrate by metal-organic chemical vapour deposition

The room-temperature and high-temperature theta -2 theta X-ray diffraction patterns of the PbTiO3 thin films grown on SrTiO3(001) substrates by metal-organic chemical vapour deposition under reduced pressure show that the epitaxial PbTiO3 thin film has a smaller c-axis length and a higher phase transition temperature than does the bulk material. The coexistence of a and c domains has also been found through the changing temperature X-ray diffraction pattern of the as-grown film. Taking the additional strain items into consideration the original Landau-Ginzburg-Devonshire form of the elastic Gibbs free energy of the PbTiO3 thin film is different from that of the bulk material, upon this, a relationship between the phase transition temperature and c-axis strain in the epitaxial film has been proposed. The reason for the c-axis length shortening has been discussed.

(001) textured PbTiO3 thin films grown on redopingn-Si by metalorganic chemical vapor deposition under reduced pressure

Abstract(001) textured PbTiO3 thin films have been deposited on (001) redopingn-Si substrates by metalorgnic chemical vapor deposition (MOCVD) under reduced pressure, and the film ferroelectricity has been measured using the substrate as bottom electrode directly. Besides this investigation, a set of analysis including AFM surface morphology, SEM cross section morphology, electron-probe element analysis, XRD 0-20 scan and high temperature X-ray diffraction have been carried out to study the microstructure and phase transition process of the PbTiO3 thin film.

Effects of anneal atmosphere on the structural and ferroelectric properties of SrBi2Ta2O9 thin films

Abstract SrBi2Ta2O9 (SBT) films were prepared on Pt/TiO2/SiO2/Si substrates at 750°C in oxygen by metalorganic decomposition method. SBT film capacitors were re-annealed in Ar (N2) at 350-750°C and then followed the O2 recovery at 750°C. Effects of anneal atmosphere on the structure, morphology and ferroelectric properties have been investigated deeply. After above 550°C 100% Ar or N2 reanneal, the remnant polarization decreases and coercive field increases significantly. The subsequent O2 recovery can hardly rejuvenated them. The result is different from that from forming gas processing (annealing in hydrogen atmosphere). The possible origin and mechanism is discussed and proposed.