Large remanent polarization of (Bi,Nd)4Ti3O 12 epitaxial thin films grown by metalorganic chemical vapor deposition

Takashi Kojima, Tomohiro Sakai, Takayuki Watanabe, Hiroshi Funakubo, Keisuke Saito, Minoru Osada

Research output: Contribution to journalArticle

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Abstract

(104)-oriented Bi4Ti3O12, La-substituted Bi4Ti3O12[(Bi3.44La 0.56)Ti3O12] and Nd-substituted Bi 4Ti3O12[(Bi3.54Nd 0.46)Ti3O12] films were epitaxially grown on (111)SrRuO3//(111)SrTiO3 substrates at 700°C by metalorganic chemical vapor deposition. All deposited films showed strong (104) orientations. The values of the remanent polarization (Pr) and coercive field (Ec) of the (104)-oriented epitaxial (Bi 3.54Nd0.46)Ti3O12 thin film were 25 μC/cm2 and 135 kV/cm, respectively. This Pr value was larger than that of the (104)-oriented (Bi3.44La0.56) Ti3O12 film: Pr and Ec values of the (Bi3.44La0.56)Ti3O12 were 17 μC/cm2 and 145 kV/cm, respectively. These good ferroelectric properties of (Bi3.54Nd0.46)Ti3O12 films can be explained by a large tilting of TiO6 octahedra induced by the substitution of Nd3+, the ionic radius of which is smaller than that of La3+. Moreover, this Pr value is almost equal to that of commercially used lead zirconate titanate (PZT) films for nonvolatile ferroelectric random access memory (FeRAM) applications. These (104)-oriented epitaxial (Bi3.54Nd0.46)Ti 3O12 thin films also showed a fatigue-free character. As a result, lead-free Nd-substituted Bi4Ti3O12 films with good ferroelectric properties comparable with those of PZT films are useful candidates for FeRAM applications.

Original languageEnglish
Pages (from-to)2746-2748
Number of pages3
JournalApplied Physics Letters
Volume80
Issue number15
DOIs
Publication statusPublished - 2002 Apr 15
Externally publishedYes

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metalorganic chemical vapor deposition
polarization
thin films
random access memory
substitutes
radii

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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Large remanent polarization of (Bi,Nd)4Ti3O 12 epitaxial thin films grown by metalorganic chemical vapor deposition. / Kojima, Takashi; Sakai, Tomohiro; Watanabe, Takayuki; Funakubo, Hiroshi; Saito, Keisuke; Osada, Minoru.

In: Applied Physics Letters, Vol. 80, No. 15, 15.04.2002, p. 2746-2748.

Research output: Contribution to journalArticle

Kojima, Takashi ; Sakai, Tomohiro ; Watanabe, Takayuki ; Funakubo, Hiroshi ; Saito, Keisuke ; Osada, Minoru. / Large remanent polarization of (Bi,Nd)4Ti3O 12 epitaxial thin films grown by metalorganic chemical vapor deposition. In: Applied Physics Letters. 2002 ; Vol. 80, No. 15. pp. 2746-2748.
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AU - Saito, Keisuke

AU - Osada, Minoru

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N2 - (104)-oriented Bi4Ti3O12, La-substituted Bi4Ti3O12[(Bi3.44La 0.56)Ti3O12] and Nd-substituted Bi 4Ti3O12[(Bi3.54Nd 0.46)Ti3O12] films were epitaxially grown on (111)SrRuO3//(111)SrTiO3 substrates at 700°C by metalorganic chemical vapor deposition. All deposited films showed strong (104) orientations. The values of the remanent polarization (Pr) and coercive field (Ec) of the (104)-oriented epitaxial (Bi 3.54Nd0.46)Ti3O12 thin film were 25 μC/cm2 and 135 kV/cm, respectively. This Pr value was larger than that of the (104)-oriented (Bi3.44La0.56) Ti3O12 film: Pr and Ec values of the (Bi3.44La0.56)Ti3O12 were 17 μC/cm2 and 145 kV/cm, respectively. These good ferroelectric properties of (Bi3.54Nd0.46)Ti3O12 films can be explained by a large tilting of TiO6 octahedra induced by the substitution of Nd3+, the ionic radius of which is smaller than that of La3+. Moreover, this Pr value is almost equal to that of commercially used lead zirconate titanate (PZT) films for nonvolatile ferroelectric random access memory (FeRAM) applications. These (104)-oriented epitaxial (Bi3.54Nd0.46)Ti 3O12 thin films also showed a fatigue-free character. As a result, lead-free Nd-substituted Bi4Ti3O12 films with good ferroelectric properties comparable with those of PZT films are useful candidates for FeRAM applications.

AB - (104)-oriented Bi4Ti3O12, La-substituted Bi4Ti3O12[(Bi3.44La 0.56)Ti3O12] and Nd-substituted Bi 4Ti3O12[(Bi3.54Nd 0.46)Ti3O12] films were epitaxially grown on (111)SrRuO3//(111)SrTiO3 substrates at 700°C by metalorganic chemical vapor deposition. All deposited films showed strong (104) orientations. The values of the remanent polarization (Pr) and coercive field (Ec) of the (104)-oriented epitaxial (Bi 3.54Nd0.46)Ti3O12 thin film were 25 μC/cm2 and 135 kV/cm, respectively. This Pr value was larger than that of the (104)-oriented (Bi3.44La0.56) Ti3O12 film: Pr and Ec values of the (Bi3.44La0.56)Ti3O12 were 17 μC/cm2 and 145 kV/cm, respectively. These good ferroelectric properties of (Bi3.54Nd0.46)Ti3O12 films can be explained by a large tilting of TiO6 octahedra induced by the substitution of Nd3+, the ionic radius of which is smaller than that of La3+. Moreover, this Pr value is almost equal to that of commercially used lead zirconate titanate (PZT) films for nonvolatile ferroelectric random access memory (FeRAM) applications. These (104)-oriented epitaxial (Bi3.54Nd0.46)Ti 3O12 thin films also showed a fatigue-free character. As a result, lead-free Nd-substituted Bi4Ti3O12 films with good ferroelectric properties comparable with those of PZT films are useful candidates for FeRAM applications.

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