Ferroelectric Properties in Ca Substituted SrBi2Nb2O9 Thin Films

2002 ◽  
Vol 748 ◽  
Author(s):  
Rasmi R. Das ◽  
W. Pérez ◽  
P. Bhattacharya ◽  
Ram S. Katiyar
Keyword(s):  
Thin Films ◽  
Dielectric Permittivity ◽  
Ferroelectric Properties ◽  
Lattice Parameter ◽  
Partial Substitution ◽  
Homogeneous Distribution ◽  
Silicon Substrates ◽  
Ionic Radii ◽  
Structural And Electrical Properties ◽  
Polarization Axis

ABSTRACTWe have studied the influence of partial substitution of Ca (0%, 5%, 10% and 15%) on the structural and electrical properties of SrBi2Nb2O9 (SBN) thin films. Pulsed laser deposition technique was used to grow thin films on platinized silicon substrates. X-ray diffraction data confirmed the polycrystalline nature of the films with preferential orientation along the polarization axis. Incorporation of Ca at Sr-site of SBN reduced the lattice parameter and was attributed to the smaller ionic radii of Ca. The soft mode frequency at 29.5 cm-1 of SBN shifted towards higher wavenumber implied increasing the transition temperature upon Ca substitution. The grain sizes of SBN thin films vary from oval to rod like structures and improving the homogeneous distribution of grains with the increase in Ca contents. The ferroelectric properties of the films enhanced with maximum remanent polarization of 35.3 mC/cm2. The increase in the coercive field with incorporation of Ca at Sr-site was attributed to the higher electronegativity of Ca. The SBN thin films with the incoporation of Ca exhibited poor leakage current behavior. The reduction of dielectric permittivity with Ca concentration was attributed to the lower dielectric permittivity of CaBi2Nb2O9.

Influence of Vanadium Doping on Structural and Ferroelectric Properties of Laser Ablated SrBi2Ta2O9 Thin Films

2002 ◽  
Vol 718 ◽  
Author(s):  
Rasmi R. Das ◽  
P. Bhattacharya ◽  
W. Pérez ◽  
Ram S. Katiyar
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Ferroelectric Properties ◽  
Lattice Parameter ◽  
Partial Replacement ◽  
Processing Temperature ◽  
Ionic Radii ◽  
Vanadium Concentration ◽  
Vanadium Doping ◽  
Stretching Vibration

AbstractPulsed laser deposition technique was used to fabricate SrBi2Ta2O9 (SBT) thin films with partial replacement of penta-valent vanadium ion. In this report, we have doped certain concentrations (0, 5, 10, 15 %) of vanadium at Ta-site of SBT thin films and study their influence on the structural and electrical characteristics. Thin films were grown on platinized silicon substrates using an excimer laser (KrF, 248 nm) with an energy density of ∼ 2.5 J/cm2. Xray diffraction studies confirmed the c-axis suppression of the films at lower processing temperature and at higher annealing temperatures. The decrease in the lattice parameter with vanadium doping was attributed to the smaller ionic radii of vanadium in comparison to Ta. Raman modes of SBT thin films shifted to higher frequencies upon vanadium incorporation at Ta-site. The extra Raman mode observed around ∼860 cm-1, was attributed due to the octahedron stretching vibration in the presence of vanadium at the center of octahedral cage. SBT thin films with 5% V doping exhibit enhanced ferroelectric properties, and the ferroelectric properties were degraded for higher vanadium concentration. The SBT thin films show dielectric constant of about ∼258 with tangential loss of 0.02 at a frequency of 100 kHz. Dielectric constant decreases with increase in V-concentration and attributed to the interdiffusion of bismuth into platinum electrode. The leakage current density of the films was also increased upon vanadium incorporation in SBT thin films.

Effect of Bottom Electrodes on Structural and Electrical Properties of Laser Ablated SrBi2Ta2O9 Thin Films

2001 ◽  
Vol 688 ◽  
Author(s):  
Rasmi R. Das ◽  
W. Pérez ◽  
P. Bhattacharya ◽  
Ram. S. Katiyar
Keyword(s):  
Thin Films ◽  
Barrier Height ◽  
Ferroelectric Properties ◽  
High Resistivity ◽  
Emission Model ◽  
X Ray Diffraction ◽  
Oxide Electrodes ◽  
Maximum Value ◽  
Structural And Electrical Properties ◽  
Raman Modes

AbstractWe have grown SrBi2Ta2O9 (SBT) thin films on various bottom electrodes such as Pt/TiO2/SiO2/Si (Pt) and LaNiO3/Pt/TiO2/SiO2/Si (LNO) substrates. The substrate temperature and oxygen pressure for the SBT film was maintained at 500 °C and 200 mTorr. As-grown films were post-annealed at a temperature of 800 °C. X-ray diffraction studies revealed that as-grown films were amorphous and crystallized to single phase after annealing. The difficulty of obtaining lowest Raman modes of SBT on platinized silicon substrate was overcome by using conducting oxide electrodes. Films grown on platinized silicon showed maximum value of remanent polarization (2Pr ∼ 21.5 μC/cm2) with coercive field (Ec) of ∼ 67 kV/cm. The degradation of ferroelectric properties of the films was observed with the introduction of 50 nm conducting LaNiO3 electrode at the interface of Pt and SBT film, which was attributed to high resistivity of the oxide electrode layers. Leakage current density was studied with the consideration of the Schottky emission model. The barrier height of the films grown on Pt and LNO were estimated to be 1.27 eV and 1.12 eV, respectively. The reduction of barrier height was attributed to the lower work function of the LNO electrode.

The Sensitivity of V2O5:Sm2O3 Thin Films against NO2 Toxic Gas

2021 ◽  
Vol 19 (3) ◽  
pp. 69-77
Author(s):  
A.J. Noori ◽  
R.A. Ahmed ◽  
I.M. Ibrahim
Keyword(s):  
Thin Films ◽  
Energy Gap ◽  
Homogeneous Distribution ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Laser Method ◽  
Operation Temperature ◽  
Best Response ◽  
Diffraction Peaks ◽  
P Type

Vanadium oxide V2O5 thin films with variation doping ratios of Sm2O5 (2, 4, 6, and 8 % wt.) on corn glass and p- type silicon substrates were prepared by pulsed laser method. The X-ray diffraction peaks for V2O5 decreases with doping ratio of Sm2O3. FESEM images for V2O5 and doped thin films illustrates clusters with a homogeneous distribution in nano scale. The energy gap varied upon the increment of doping concentration, starting from 2.610 eV to 2.7 eV. Gas sensor measurement of pure and doped V2O5 demonstrated a sensitivity to NO2 gas, and the sensitivity expanded upon the increment of operation temperature. The greatest sensitivity was found to be about 99%, while best response time of 10s and recovery time of 18s were recorded using the 4% Sm2O3 sample at 50 °C.

scholarly journals Direct Comparison of Structural and Electrical Properties of Epitaxial (001)-, (116)-, and (103)-Oriented SrBi2Ta2O9 Thin Films on SrTiO3 and Silicon Substrates

2000 ◽  
Vol 655 ◽  
Author(s):  
H. N. Lee ◽  
A. Pignolet ◽  
S. Senz ◽  
C. Harnagea ◽  
D. Hesse
Keyword(s):  
Thin Films ◽  
Remanent Polarization ◽  
Bottom Electrode ◽  
Three Dimensional ◽  
Laser Deposition ◽  
Layered Perovskite ◽  
Silicon Substrates ◽  
Epitaxial Thin Films ◽  
Structural And Electrical Properties ◽  
First Time

AbstractAnisotropies of the properties of the bismuth-layered perovskite SrBi2Ta2O9 (SBT) have been investigated using epitaxial thin films grown by pulsed laser deposition both on conducting Nb-doped SrTiO3 (STO) single crystal substrates and on Si(100) substrates. It has been found that the three-dimensional epitaxy relationship SBT(001)∥STO(001); SBT [110] ∥STO[100] can be applied to all SBT thin films on STO substrates of (001), (011), and (111) orientations. An about 1.7 times larger remanent polarization was obtained in (103)-oriented SBT films than in that of (116) orientation, while the (001)-oriented SBT films revealed no ferroelectricity along their c-axis. Non-c-axis-oriented SBT films with a well-defined (116) orientation were also grown on silicon substrates for the first time. They were deposited on Si(100) covered with a conducting SrRuO3 (110) bottom electrode on a YSZ(100) buffer layer.

Effects of adhesion layers on the ferroelectric properties of lead zirconium titanate thin films deposited on silicon nitride coated silicon substrates

2008 ◽  
Vol 516 (18) ◽  
pp. 6052-6057 ◽  
Author(s):  
Omar Zohni ◽  
Gregory Buckner ◽  
Taeyun Kim ◽  
Angus Kingon ◽  
Jeff Maranchi ◽  
...  
Keyword(s):  
Thin Films ◽  
Silicon Nitride ◽  
Ferroelectric Properties ◽  
Silicon Substrates ◽  
Zirconium Titanate ◽  
Lead Zirconium Titanate

Preparation and Properties of ferroelectric Bi2SrTa2O9 thin films for FeRAM using Flash-MOCVD

1995 ◽  
Vol 415 ◽  
Author(s):  
T. Ami ◽  
K. Hironaka ◽  
C. Isobel ◽  
N. Nagel ◽  
M. Sugiyama ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Coercive Field ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Type Structure ◽  
Structural And Electrical Properties ◽  
Fluorite Type ◽  
Deposited Films ◽  
Flowing Oxygen

ABSTRACTFerroelectric Bi2 SrTa2 O9 thin films were successfully prepared by liquid delivery MOCVD, and structural and electrical properties were investigated. As-deposited films showed sharp distinct peaks, which were indexed assuming a fluorite-type structure. These precursors were transformed to bismuth-layered structures by annealing at 800 °C in flowing oxygen. Reasonable ferroelectric properties were observed in a film with 170 nm-thickness. Remanent polarization and coercive field were estimated to be 5.2 μC/cm2 and 52 kV/cm, respectively, at 5V.

Internal Stress In Sputtered Silver Nickel Thin Films And Multilayers: Sputtering Pressure And Thickness Effects

1999 ◽  
Vol 562 ◽  
Author(s):  
P. Gergaud ◽  
H. Yang ◽  
C. PéLissonnier-Grosjean ◽  
A. J. Bottger ◽  
P. Sandström ◽  
...  
Keyword(s):  
Thin Films ◽  
Internal Stress ◽  
Layer Thickness ◽  
Lattice Parameter ◽  
Free Lattice ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Nickel Thin Films ◽  
The Individual ◽  
20 Nm

ABSTRACTNanometer thick films are often in a state of high residual stress. This may strongly influence physical properties such as magnetic anisotropy. The aim of our study is to investigate whether the overall stress in multilayers may be tailored via the control of the sputtering parameters or of the individual thicknesses. The coatings investigated were deposited at room temperature by magnetron sputtering on oxidised silicon substrates. Ag/Ni multilayers of superperiod between 4 to 20 nm and thin films (Ag or Ni) 200 nm thick have been deposited under a krypton partial pressure varying between 1 and 8 mTorr. Internal stress measurements were performed by curvature method and x-ray diffraction sin2ψ method. The latter one allows the determination of the stress and of the stress-free lattice parameter in the Ag or the Ni layers whereas the first one gives rise to a measure of the average stress in the coating. The main results are the followings: (i) The stress in Ni thin films changes from compressive to tensile at a pressure between 2 and 5 mTorr whereas Ag thin films are sligthly tensile whatever the pressure; (ii) The stress in multilayers is tensile in Ag and Ni and decreases with sublayer thickness; (iii) The stress free lattice parameter of Ag in thin films or multilayers is independent of the Kr pressure and of the layer thickness and is equal to the bulk value; (iv) On the opposite, the stress-free lattice parameter of nickel decreases with the layer thickness in multilayers and is equal to the bulk value in thin films. These results are discussed in terms of the respective influence of interfacial intermixing and atomic peening mechanism.

Structural and Ferroelectric Properties of SrBi2Ta2O9 Thin Films

1994 ◽  
Vol 361 ◽  
Author(s):  
Kazushi Amanuma ◽  
Takashi Hase ◽  
Yoicht Mtyasaka
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Structural Change ◽  
Electrical Properties ◽  
Ferroelectric Properties ◽  
Si Substrates ◽  
Average Grain Size ◽  
Structural And Electrical Properties ◽  
Sims Analysis ◽  
Film Preparation

ABSTRACTStructural and electrical properties were investigated for chemically prepared SrBi2Ta2O9(SBT) thin films on Pt/Ti/SiO2/Si substrates. Good ferroelectric properties were obtained with a Pt top electrode: Pr=10.0μC/cm2 and Ec-34kV/cm. Au top electrodes resulted in smaller Pr. However, no fatigue was observed up to 109 switching cycles regardless of the top electrode material. Grains were spherical, not columnar, and the average grain size was 200nm. A marked structural change took place in the bottom Pt/Ti electrode during film preparation. The SIMS analysis indicates the reaction between Bi and Pt

Effect of Cationic Substitution on Raman Spectra of SrBi2Ta2O9Ceramics and Thin Films

2003 ◽  
Vol 784 ◽  
Author(s):  
W. Perez ◽  
R. R. Das ◽  
P. S. Dobal ◽  
Y. I. Yuzyuk ◽  
P. Bhattacharya ◽  
...  
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Lattice Mismatch ◽  
Ferroelectric Properties ◽  
Low Frequency ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
Cationic Substitution ◽  
Factor Substitution ◽  
Raman Modes

ABSTRACTIn the present work micro-Raman spectroscopy has been used to understand the lattice dynamics of cation substituted SBT ceramics and thin films. Different concentrations of Ca and V were introduced into SBT lattices. Incorporation of Ca ion at Sr-site was confirmed by decrease in the lattice parameters calculated from x-ray diffraction data. The lowest Raman modes at 27 cm-1and 58 cm-1showed upward shift with increasing Ca concentration and was attributed to the lower mass and lower ionic radii of Ca. The temperature dependant Raman studies revealed the increase of the phase transition temperature with increased Ca content, and was attributed to the decrease in tolerance factor. Substitution of smaller cation at Sr site in SBT compound has increased lattice mismatch between SrO and TaO2planes inside the stable perovskite unit of SrTa2O7which has pronounced influence on ferroelectric properties of SBT. Substitution of vanadium at Ta-site of SBT did not influence the low frequency Raman modes of SBT. However, it showed a pronounced influence on the O-Ta-O stretching modes by splitting the mode frequency at 810 cm-1. The transition temperature of SBT was reduced with increasing vanadium contents.

Lanthanide series doping effects in lead zirconate titanate (PLnZT) thin films

2002 ◽  
Vol 17 (4) ◽  
pp. 871-878 ◽  
Author(s):  
Timothy J. Boyle ◽  
Paul G. Clem ◽  
Bruce A. Tuttle ◽  
Geoffrey L. Brennecka ◽  
Jeffrey T. Dawley ◽  
...  
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Hysteresis Loops ◽  
Lead Zirconate ◽  
Lattice Parameter ◽  
Zirconate Titanate ◽  
Doping Effects ◽  
Structural And Electrical Properties ◽  
Tan Δ ◽  
Parameter Values

Lanthanide (Ln) doping of lead zirconate titanate (PLnZT 4/30/70) thin films was conducted to investigate effects on structural and electrical properties. Films were spin-coat deposited from precursor solutions made using a previously reported “basic route to PZT” chemistry. The remanent polarization (Pr), dielectric constant (ε), dielectric loss (tan δ), and lattice parameter values were obtained for each of the doped PLnZT films. Films doped with amphoteric cations (Tb, Dy, Y, and Ho) displayed high Pr values, square hysteresis loops, and enhanced fatigue resistance. Smaller radius Ln-doped films display an increased tendency toward (100) orientation in otherwise (111)-oriented films.

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