Microstructural Evolution of Epitaxial LiNbO3 Thin Films Derived From Metal Alkoxide Solutions

1990 ◽  
Vol 202 ◽  
Author(s):  
Keiichi Nashimoto ◽  
Michael J. Cima ◽  
Wendell E. Rhine
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Single Phase ◽  
Sol Gel ◽  
Precursor Solution ◽  
Epitaxial Films ◽  
Metal Alkoxide ◽  
High Annealing Temperature ◽  
Sapphire Substrates ◽  
High Annealing

ABSTRACTThe evolution of the microstructure of sol-gel derived LiNbO3 thin films was investigated to understand the growth of epitaxial films. LiNbO3 films were prepared from a precursor solution of lithium ethoxide and niobium pentaethoxide. Prehydrolysis promoted the development of polycrys-talline LiNbO3 films, whereas nonhydrolysis produced solid-state epitaxial growth of LiNbO3 films on sapphire substrates. Although the films looked smooth after annealing at 400°C, the morphology of the films changed, depending on substrates and precursors, due to grain growth at high annealing temperature. Prehydrolysis of the alkoxides caused a decrease in the temperature at which grain growth occurred, whereas the film prepared from the nonhydrolyzed precursor on a sapphire substrate showed denser texture and contained abnormally large domains that appeared to be single phase.

scholarly journals Effect of Solution Conditions on the Properties of Sol–Gel Derived Potassium Sodium Niobate Thin Films on Platinized Sapphire Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1600 ◽  
Author(s):  
Alexander Tkach ◽  
André Santos ◽  
Sebastian Zlotnik ◽  
Ricardo Serrazina ◽  
Olena Okhay ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Low Cost ◽  
Sol Gel ◽  
Precursor Solution ◽  
Dissipation Factor ◽  
Solution Concentration ◽  
Potassium Sodium Niobate ◽  
Sapphire Substrates ◽  
Average Grain Size

If piezoelectric micro-devices based on K0.5Na0.5NbO3 (KNN) thin films are to achieve commercialization, it is critical to optimize the films’ performance using low-cost scalable processing conditions. Here, sol–gel derived KNN thin films are deposited using 0.2 and 0.4 M precursor solutions with 5% solely potassium excess and 20% alkali (both potassium and sodium) excess on platinized sapphire substrates with reduced thermal expansion mismatch in relation to KNN. Being then rapid thermal annealed at 750 °C for 5 min, the films revealed an identical thickness of ~340 nm but different properties. An average grain size of ~100 nm and nearly stoichiometric KNN films are obtained when using 5% potassium excess solution, while 20% alkali excess solutions give the grain size of 500–600 nm and (Na + K)/Nb ratio of 1.07–1.08 in the prepared films. Moreover, the 5% potassium excess solution films have a perovskite structure without clear preferential orientation, whereas a (100) texture appears for 20% alkali excess solutions, being particularly strong for the 0.4 M solution concentration. As a result of the grain size and (100) texturing competition, the highest room-temperature dielectric permittivity and lowest dissipation factor measured in the parallel-plate-capacitor geometry were obtained for KNN films using 0.2 M precursor solutions with 20% alkali excess. These films were also shown to possess more quadratic-like and less coercive local piezoelectric loops, compared to those from 5% potassium excess solution. Furthermore, KNN films with large (100)-textured grains prepared from 0.4 M precursor solution with 20% alkali excess were found to possess superior local piezoresponse attributed to multiscale domain microstructures.

Synthesis and Ferroelectric Properties of Sr- and Nb-codoped Bi4−xSrxTi3−xNbxO12 Thin Films by Sol-Gel Method

2001 ◽  
Vol 688 ◽  
Author(s):  
Hirofumi Matsuda ◽  
Takashi Iijima ◽  
Hiroshi Uchida ◽  
Isao Okada ◽  
Takayuki Watanabe ◽  
...  
Keyword(s):  
Thin Films ◽  
Curie Temperature ◽  
Spin Coating ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Metal Alkoxide ◽  
Gel Method ◽  
Maximum Value ◽  
Chemical Solutions

AbstractFerroelectric Bi4Ti3O12 (BIT) thin films were modified by the substitution of Sr2+ ions for Bi3+ ions and of Nb5+ for Ti4+ (codoping) by spin-coating and decomposition of chemical solutions of metal-alkoxide materials (the nominal compositions of Bi4−xSrxTi3−xNbxO12 where x=0.0, 0.5, 1.0, 1.5). Single-phase thin films were crystallized above 550°C with BIT-type structure. The ferroelectric properties were found, though, with the values of Pr=10 μC/cm2 Ec=100 kV/cm, εr=300, and tanδ<5 % for Bi3.5Sr0.5Ti2.5Nb0.5O12 (x=0.5) annealed at 650 °C. Perhaps due to the lowering of the Curie temperature with increasing x, the maximum value of δr increased.

Processing of Dense Nanocrystalline Zirconia Thin Films by Sol-Gel

2006 ◽  
Vol 928 ◽  
Author(s):  
Christoph Peters ◽  
Matthias Bockmeyer ◽  
Reinhard Krüger ◽  
André Weber ◽  
Ellen Ivers-Tiffée
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Rapid Thermal Annealing ◽  
Growth Phase ◽  
Sol Gel ◽  
Grain Sizes ◽  
Sapphire Substrates ◽  
Metal Organic ◽  
Nanocrystalline Zirconia ◽  
Metal Organic Deposition

ABSTRACTVia metal organic deposition (MOD) sapphire substrates were multiple dip-coated with a molecular dispersive 8 mol% Y2O3 doped ZrO2 (8YSZ) sol to prepare dense, crack-free thin films. The thin films were consecutively exposed to a tempering program with several rapid thermal annealing (RTA) steps and a final dwell temperature between 500 °C and 1400 °C for 24 h. Grain growth, phase, stoichiometry and macroscopic density of the thin films were analyzed by XRD and SEM. Grain sizes ranged between a few nanometers in diameter at 500 °C and several hundreds of nanometers at 1400 °C.

Preparation and Characterization of Sol-Gel Derived Heteroepitaxial LiNbO3 and LiTaO3 Thin Films

1993 ◽  
Vol 310 ◽  
Author(s):  
Keiichi Nashimoto
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Metal Alkoxide ◽  
Bulk Single Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Sapphire Substrates ◽  
Sol Gel Process ◽  
Alkoxide Precursors

AbstractDense epitaxial LiNbO3 thin films without any misoriented plane on sapphire substrates were obtained with a sol-gel process utilizing 2-methoxyethanol based metal alkoxide precursors without pre-hydrolysis and rapid thermal annealing. Epitaxial LiNbO3 films annealed at 700°C were transparent and showed refractive indices close to bulk single crystal values. Epitaxial and transparent LiTaO3 films crystallized successfully on sapphire substrates with single orientations with the present process. X-ray rocking curve full widths at half maximum of epitaxial LiNbO3 and LiTaO3 films on sapphire (110) substrates and annealed at 700°C were less than 0.4 degree.

Microstructure development of sol-gel derived epitaxial LiNbO3 thin films

1995 ◽  
Vol 10 (10) ◽  
pp. 2564-2572 ◽  
Author(s):  
Keiichi Nashimoto ◽  
Michael J. Cima ◽  
Paul C. McIntyre ◽  
Wendell E. Rhine
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Spin Coating ◽  
Film Growth ◽  
Intermediate Phase ◽  
Substrate Surface ◽  
Sol Gel ◽  
Precursor Solution ◽  
Epitaxial Films ◽  
Epitaxial Relationship

Film growth and microstructural evolution were investigated for sol-gel derived LiNbO3 thin films deposited on lattice-matched single-crystal substrates. Epitaxial LiNbO3 films of about 100 nm nominal thickness were prepared by spin coating a solution of the lithium niobium ethoxide on sapphire (0001) substrates and annealing at 400 °C or 700 °C in a humidified oxygen atmosphere. These films exhibited an epitaxial relationship with the substrate of the type LiNbO3 (0001) || α-Al2O3 (0001) and LiNbO3 [100] || α-Al2O3 [100] as determined by x-ray pole figure analysis. Transmission electron microscopy indicated the epitaxial films annealed at 400 °C consisted of slightly misoriented ∼5 nm subgrains and of numerous ∼10 nm enclosed pores. The microstructure and orientation development of these films was consistent with a heteroepitaxial nucleation and growth mechanism, in which epitaxial nuclei form at the substrate surface and grow upward into an amorphous and porous intermediate film: Epitaxial films annealed at 700 °C contained larger 150-200 nm subgrains and pinholes. Misorientations between adjacent subgrains appeared to be significantly smaller in films annealed at 700 °C than those in films annealed at 400 °C. Hydrolysis of the alkoxide precursor solution prior to spin coating promoted the development of polycrystalline films on single-crystal sapphire substrates. Infrared spectra and thermal analysis indicated that, independent of the degree of the solution hydrolysis, nucleation of LiNbO3 was immediately preceded by decomposition of an amorphous carbonate intermediate phase.

Effect of substrates on the crystallinity and morphology of sol-gel-derived epitaxial LiNbO3 films

1995 ◽  
Vol 10 (7) ◽  
pp. 1779-1783 ◽  
Author(s):  
K. Terabe ◽  
N. Iyi ◽  
K. Kitamura ◽  
S. Kimura
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Thermal Expansion ◽  
Grain Growth ◽  
Lattice Constant ◽  
Smooth Surface ◽  
Sol Gel ◽  
The Other ◽  
Epitaxial Thin Films ◽  
Sapphire Substrates

Epitaxial thin films of LiNbO3 were prepared by the sol-gel method on (0001)-sapphire, (0001)-LiTaO3 and (0001)-5% MgO-doped LiNbO3, substrates. The precursor films crystallized with the highly preferred orientation on all substrates. When sapphire substrates, which have large discrepancies in the lattice constant and thermal expansion percentage with the film were used, the resulting films showed a low crystallinity after heat treatment at 500 °C and grain growth at 650 °C. On the other hand, when using LiTaO3 and 5% MgO-doped LiNbO3 substrates, with smaller discrepancies, the formed films, after heat treatment at 500 °C, showed better crystallinity with the smooth surface.

Sol-gel synthesis of textured lanthanum titanate thin films

2003 ◽  
Vol 18 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Mary M. Sandstrom ◽  
Paul Fuierer
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Precursor Solution ◽  
Solution Concentration ◽  
Optical Measurements ◽  
Layered Perovskite ◽  
Orientation Factor ◽  
Anisotropic Structures ◽  
Sol Gel Films ◽  
Sol Gel Synthesis

Control over crystallographic orientation in thin films is important, particularly with highly anisotropic structures. Because of its ferroelectric nature, the layered perovskite La2Ti2O7 has interesting piezoelectric and electrooptic properties that may be exploited when films are highly textured. Sol-gel films with an orientation factor of greater than 95% were fabricated without relying on epitaxial (lattice-matching) growth from the substrate. Film orientation and crystallization were confirmed by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and optical measurements. The particle sizes in all precursor solutions were measured by dynamic light scattering experiments. Experimental results indicate that film orientation is a function of precursor solution concentration, size of the molecular clusters in the solution, and film thickness.

Chemical Vapor Deposition of Sr1−xBaxNb2O6 Thin Films Using Metal Alkoxide Precursors

2000 ◽  
Vol 15 (8) ◽  
pp. 1702-1708
Author(s):  
Ruichao Zhang ◽  
Ren Xu
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Single Phase ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Thin Layers ◽  
Metal Alkoxide ◽  
Stoichiometry Control ◽  
Alkoxide Precursors

A novel two-step metalorganic chemical vapor deposition process was used in this study to prepare Sr1−xBaxNb2O6 (SBN) thin films. Two thin layers of single-phase SrNb2O6 and BaNb2O6 were deposited alternately on a silicon substrate, and the solid solution of SBN was obtained by high-temperature annealing. The stoichiometry control of the SrNb2O6 and the BaNb2O6 thin films was achieved through deposition process control, according to the evaporation characteristics of double metal alkoxide. The evaporation behavior of double metal alkoxide precursors SrNb2(1-OC4H9)12 and BaNb2(1-OC4H9)12 was studied, and the results were compared with the evaporation of single alkoxide Nb(1-OC4H9)5.

ITO Thin Films on Silicon Buffer by Sol Gel Method

2006 ◽  
Vol 514-516 ◽  
pp. 1155-1160 ◽  
Author(s):  
Talaat Moussa Hammad
Keyword(s):  
Thin Films ◽  
Indium Tin Oxide ◽  
Optical Transmission ◽  
Sol Gel ◽  
Precursor Solution ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ito Thin Films ◽  
Uv Visible

Sol gel indium tin oxide thin films (In: Sn = 90:10) were prepared by the sol-gel dipcoating process on silicon buffer substrate. The precursor solution was prepared by mixing SnCl2.2H2O and InCl3 dissolved in ethanol and acetic acid. The crystalline structure and grain orientation of ITO films were determined by X-ray diffraction. The surface morphology of the films was characterized by scanning electron microscope (SEM). Optical transmission and reflectance spectra of the films were analyzed by using a UV-visible spectrophotometer. The transport properties of majority charge carriers for these films were studied by Hall measurement. ITO thin film with electrical resistivity of 7.6 ×10-3 3.cm, Hall mobility of approximately 2 cm2(Vs)-1 and free carrier concentration of approximately 4.2 ×1020 cm-3 are obtained for films 100 nm thick films. The I-V curve measurement showed typical I-V characteristic behavior of sol gel ITO thin films.

Effect of Precursor Sol Ageing on Sol-Gel Derived Ruthenium Oxide Thin Films

1999 ◽  
Vol 606 ◽  
Author(s):  
S. Bhaskar ◽  
S. B. Majumder ◽  
P. S. Dobal ◽  
R. S. Katiyar ◽  
A. L. M. Cruz ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Ruthenium Oxide ◽  
Precursor Solution ◽  
Silicon Substrates ◽  
Solution Deposition ◽  
Precursor Material ◽  
Afm Analysis

AbstractIn the present work we have optimized the process parameters to yield homogeneous, smooth ruthenium oxide (RuO2) thin films on silicon substrates by a solution deposition technique using RuCl3.×.H2O as the precursor material. Films were annealed in a temperature range of 300°C to 700°C, and it was found that RuO2 crystallizes at a temperature as low as 400°C. The crystallinity of the films improves with increased annealing temperature and the resistivity decreases from 4.86µΩ-m (films annealed at 400°C) to 2.94pµΩ (films annealed at 700°C). Ageing of the precursor solution has a pronounced effect on the measured resistivities of RuO2 thin films. It was found that the measured room temperature resistivities increases from 2.94µΩ-m to 45.7µΩ-m when the precursor sol is aged for aged 60 days. AFM analysis on the aged films shows that the grain size and the surface roughness of the annealed films increase with the ageing of the precursor solution. From XPS analysis we have detected the presence of non-transformed RuCl3 in case of films prepared from aged solution. We propose, that solution ageing inhibits the transformation of RuCl3 to RuO2 during the annealing of the films. The deterioration of the conductivity with solution ageing is thought to be related with the chloride contamination in the annealed films.

Sign in / Sign up

Export Citation Format

Share Document