Orientation Control of Sr0.7Bi2.3Ta2O9+α Thin Films by Chemical Liquid Deposition

Koiwa, Ichiro; Kanehara, Takao; Mita, Juro; Iwabuchi, Toshiyuki; Osaka, Tetsuya; Ono, Satoshi

doi:10.1143/jjap.36.1597

Cited by 21 publications

(8 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect of composition of the precursor solutions on the formation of SBT films prepared by CSD has been previously studied by other authors. 18,19 Compositions with small deviations of strontium and/or bismuth from the stoichiometric one (SrBi 2 Ta 2 O 9 ) can give rise to the formation of second phases. SBT precursor solutions containing stoichiometric Bi and a large Sr defect can lead to SBT films with bismuth tantalate, BiTaO 4 , as second phase.…”

Section: Discussionmentioning

confidence: 99%

Crystallization, Heterostructure, Microstructure, and Properties of Ferroelectric Strontium Bismuth Tantalate Films Derived from Tantalum Glycolate Solutions

et al. 2003

View full text Add to dashboard Cite

Strontium bismuth tantalate (SBT) films were prepared by chemical solution deposition (CSD) onto Pt/TiO 2 /SiO 2 /(100)Si substrates. Nominal chemical compositions of the precursor solutions of SrBi 2 Ta 2 O 9 , SrBi 2.2 Ta 2 O 9 , Sr 0.8 Bi 2 Ta 2 O 9 , and Sr 0.8 Bi 2.2 Ta 2 O 9 were tested for the deposition of the films. Crystallization of the films was carried out by a two-step process (TS) or a single-step process (SS). The TS treatment consisted of thermal treatment of the films in oxygen atmosphere at 550°C for 7200 s, with a heating rate of 8°C/s, followed by a rapid thermal processing (RTP) in oxygen at a temperature of 650°C for 3600 s, using a heating rate of 200°C/s. The SS process was just the RTP treatment of the films. The X-ray diffraction (XRD) patterns of the crystalline films showed the formation of the layered perovskite together with a second phase. Analysis of the films by means of Rutherford backscattering spectroscopy (RBS) showed that this second phase was placed at the interface and it was formed by the reaction of the film and the substrate. Composition and thickness of this interface as well as profile composition of the SBT layer were also analyzed by RBS. These studies indicated that the heterostructure of the films was related with their nominal composition and with the type of thermal treatment used for their crystallization. Both parameters, composition and treatment, also determined the surface microstructures of the films. Dielectric and ferroelectric properties of the films were measured and related with their composition, heterostructure, and microstructure. The best hysteresis loops with the maximum values of remanent polarization, P r , were obtained for the films with nominal composition of Sr 0.8 Bi 2.2 Ta 2 O 9 and crystallized with the SS treatment. These films have a low fatigue up to ∼10 11 cycles, a retention of the polarization over 10 5 seconds, and leakages of <10 -7 µA/cm 2 at 300 kV/cm.

show abstract

Section: Discussionmentioning

confidence: 99%

Crystallization, Heterostructure, Microstructure, and Properties of Ferroelectric Strontium Bismuth Tantalate Films Derived from Tantalum Glycolate Solutions

et al. 2003

View full text Add to dashboard Cite

show abstract

“…8,9 For comparison, some specimens were prepared from mixed alkoxide solution and complexed alkoxide solution. The composition of the solutions was adjusted to atomic ratio Sr : Bi : Ta D 0.9 : 2.1 : 2.0.…”

Section: Methodsmentioning

confidence: 99%

Metallic bismuth on strontium-bismuth tantalate thin films for ferroelectric memory application

Asami

Osaka

Yamanobe

et al. 2000

Surf. Interface Anal.

Self Cite

View full text Add to dashboard Cite

Strontium-bismuth tantalate (SBT) has been actively investigated as an attractive candidate for non-volatile ferroelectric random access memories because of its high resistance to fatigue. However, the ferroelectric property of SBT is easily affected by fabrication process parameters. The relationship between the surface chemistry of SBT thin films and the fabrication process parameters, such as crystallization temperature, upper Pt electrode, annealing in oxygen after Pt electrode fabrication (= the second annealing), hydrogen sintering and ion etching, were examined mainly by XPS analysis. In all specimens, metallic Bi, which is one of the main causes for deterioration of their performances, was observed in addition to oxidic Bi, Sr and Ta. The deposition of an upper Pt electrode resulted exclusively in an increase in metallic Bi content. Sintering in a hydrogen atmosphere and ion etching increased the ratio of metallic Bi to total Bi. The second annealing was effective in suppressing the metallic Bi content.

show abstract

“…The film exhibits well-defined P-E hysteresis loops without fatigue after being subjected to 10 11 switching cycles, even when the annealing temperature of the film was as low as 700ЊC. 8,9 Although the annealing temperature of SBT thin film is generally required to be as high as 800ЊC to obtain satisfactory fatigue properties, we found that the lower annealing temperature suffices with our film. Furthermore, it was confirmed [7][8][9][10][11][12] that the film, composed of microcrystallites of fluorite phase at 650ЊC, undergoes a structure change at 700ЊC into a mixture of large single-crystal grains of bismuth-layered perovskite (SBT) and residual microcrystallites, and finally, the microcrystallite region almost vanishes at 800ЊC.…”

mentioning

confidence: 80%

“…Recently, we 8,9 reported on new SBT thin films fabricated by a chemical liquid deposition method using an alkoxide with four or less carbon atoms as the raw material. The film exhibits well-defined P-E hysteresis loops without fatigue after being subjected to 10 11 switching cycles, even when the annealing temperature of the film was as low as 700ЊC.…”

mentioning

confidence: 99%

Characterization of Ferroelectric SrBi2Ta2 O 9 Thin Films Prepared from Alkoxide Solutions

Ono¹,

Sakakibara²,

Osaka³

et al. 1999

J. Electrochem. Soc.

View full text Add to dashboard Cite

SrBi2Ta2O9 thin films prepared by chemical liquid deposition using alkoxide precursor solutions, followed by annealing at various temperatures, were characterized with a focus on the correlation between composition, microstructure, and ferroelectric properties. P-E hysteresis loops of the films exhibited well‐defined shapes at temperatures above 700°C, and the leakage current decreased with increasing annealing temperature, except for a film annealed at 4750°C. The crystal growth proceeded and ferroelectric properties of the films improved with increasing annealing temperature, whereas a large leakage current was observed for the film annealed at 750°C. Quantitative X‐ray photoelectron specroscopic analysis and high‐resolution transmission electron microscopic observation indicated the presence of a substantial amount of metallic bismuth in all films, predominantly in microcrystallite regions and on film surfaces, including the inner surface of cavities. The atomic fraction of metallic bismuth increased upon slight argon etching; however, the total bismuth content was significantly reduced. The metallic bismuth was amorphous and detected as vibrating spherical particles measuring approximately 5 nm under electron irradiation. The discontinuity in morphology, such as cavities at the interface between large single‐crystal grains and microcrystallite regions, was most remarkable in the film annealed at 750°C. The condensation of metallic bismuth at the cavities is believed to increase the leakage current when the path formed by cavities penetrates through the film. © 1999 The Electrochemical Society. All rights reserved.

show abstract

Orientation Control of Sr_0.7Bi_2.3Ta₂O_9+α Thin Films by Chemical Liquid Deposition

Cited by 21 publications

References 6 publications

Crystallization, Heterostructure, Microstructure, and Properties of Ferroelectric Strontium Bismuth Tantalate Films Derived from Tantalum Glycolate Solutions

Crystallization, Heterostructure, Microstructure, and Properties of Ferroelectric Strontium Bismuth Tantalate Films Derived from Tantalum Glycolate Solutions

Metallic bismuth on strontium-bismuth tantalate thin films for ferroelectric memory application

Characterization of Ferroelectric SrBi2Ta2 O 9 Thin Films Prepared from Alkoxide Solutions

Contact Info

Product

Resources

About