Optical properties of highly reduced<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">SrTiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>

Crandles, D. A.; Nicholas, B.; Dreher, Cornelia; Homes, C. C.; McConnell, A. W.; Clayman, B. P.; Gong, Wanjun; Greedan, J. E.

doi:10.1103/physrevb.59.12842

Cited by 70 publications

(48 citation statements)

References 22 publications

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“…26, 27 Crandles et al studied highly reduced SrTiO 3−δ by using optical spectroscopy. 23 They observed broadening of the phonon modes with an increase in the oxygen vacancy, V O , density as well as V O -induced mid-infrared band whose strength scales with carrier concentration. 23 The most reduced sample, SrTiO 2.72 , displayed a localization-modified Drude optical conductivity that was attributed to the dynamic disorder introduced by the oxygen vacancies.…”

Section: Introductionmentioning

confidence: 99%

“…23 They observed broadening of the phonon modes with an increase in the oxygen vacancy, V O , density as well as V O -induced mid-infrared band whose strength scales with carrier concentration. 23 The most reduced sample, SrTiO 2.72 , displayed a localization-modified Drude optical conductivity that was attributed to the dynamic disorder introduced by the oxygen vacancies. 23 In the most recent studies, enhancement of effective electron mass by a factor of 2-3 has been deduced from a narrow Drude peak and mid-infrared (MIR) absorption band in the Nb-doped SrTiO 3 .…”

Section: Introductionmentioning

confidence: 99%

“…23 The most reduced sample, SrTiO 2.72 , displayed a localization-modified Drude optical conductivity that was attributed to the dynamic disorder introduced by the oxygen vacancies. 23 In the most recent studies, enhancement of effective electron mass by a factor of 2-3 has been deduced from a narrow Drude peak and mid-infrared (MIR) absorption band in the Nb-doped SrTiO 3 . 25 It is worth mentioning that the origin of the MIR band in cuprates, nickelates and titanates remains controversial.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the literature so far has been dedicated to n-type SrTiO 3 , [21][22][23][24][25] and only a limited number of papers have addressed optical properties of n-type BaTiO 3 . 26, 27 Crandles et al studied highly reduced SrTiO 3−δ by using optical spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

et al. 2010

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We report on optical properties of reduced BaTiO 3−δ at different doping levels including insulating and metallic samples. In all the samples, including metallic one, we observe structural phase transitions from the changes of the infrared active phonon modes. Metallic ground state is confirmed by the Drude-type low-frequency optical reflectance. Similar to SrTiO 3−δ we find that the mid-infrared absorption band in BaTiO 3−δ appears and grows with an increase in the oxygen vacancy concentration. Upon decrease in temperature from 300 K, the mid-infrared band shifts slightly to higher frequency and evolves into two bands: the existing band and a new and smaller band at lower frequency. The appearance of the new and smaller band seems to be correlated with the structural phase transitions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

et al. 2010

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“…By contrast, the softening and linewidth decrease of the LO and TO absorption peaks for the H doped sample suggest a decrease in numbers of charge carriers. [10][11][12] It is worth noting that, for the control sample, there are three small shoulders in the peak corresponding to the Ti-O stretching modes at 570-585 cm Ϫ1 , while there is only a single peak at 580 cm Ϫ1 for the hydrogen doped sample. 13 This indicates that H doping may relax the Ti-O bonds and the crystal lattice.…”

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confidence: 99%

Ambient-temperature incorporated hydrogen in Nb:SrTiO3 single crystals

Chen

Pang

Lee

et al. 2003

Applied Physics Letters

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Electrolysis of water has been implemented to inject hydrogen into the SrTiO 3 single crystal doped with 1 wt % of Nb. Direct evidence of OH Ϫ group formation in the Nb:SrTiO 3 single crystal has been obtained by Fourier-transform infrared ͑FTIR͒ analysis, showing an intensity increase of the absorption at a wave number of about 3500 cm Ϫ1 . FTIR analysis also revealed lattice relaxation due to hydrogen doping. High-resolution x-ray diffraction ͑XRD͒ analysis further illustrated lattice expansion, as evidenced by the left shift of the SrTiO 3 ͑200͒ peak for the hydrogen doped sample. The decrease in the XRD rocking curve linewidth of this ͑200͒ peak for the hydrogen-doped sample suggested that hydrogen doping relaxed the local constraints in the crystal. In contrast to the usual great increase in conductivity of insulating perovskite oxides by hydrogen doping, an obvious decrease in conductivity of the highly conductive Nb:SrTiO 3 single crystal was observed after hydrogen doping. In recent years, much attention has been paid to the reactions and impact of hydrogen on perovskite ferroelectric oxides. Even though perovskite oxides are widely used in ceramic capacitors and piezoelectric devices, the reaction between hydrogen and (Ba,Sr)TiO 3 or Pb(Zr,Ti)O 3 thin film capacitors during forming gas annealing ͑FGA͒ and the consequent degradation is a major obstacle to their integration as nonvolatile memories in complementary metal-oxidesemiconductor based devices. 1,2 Chen and co-workers recently found that the ambient temperature reaction of atomic hydrogen generated by electrolysis of water causes serious problems of reliability in (Ba,Sr)TiO 3 and Pb(Zr,Ti)O 3 . 3,4 To date, extensive studies have been carried out to determine the mechanism of FGA degradation and the following fairly clear picture has been obtained: hydrogen incorporated into perovskite lattice as a shallow donor results in a great increase in leakage currents and an obvious depression in polarization. However, fundamental studies and in-depth understanding of the ambient-temperature reaction between atomic hydrogen and perovskite oxides are still limited.In this letter, we report direct evidence of the ambienttemperature incorporation of hydrogen in Nb doped SrTiO 3 single crystals (Nb:SrTiO 3 ) and its impact on the conductivity and structure of the crystals. SrTiO 3 is a typical perovskite oxide. Its single crystals are widely used as a substrate or buffer layer for ferroelectric films and high-T c superconducting films deposition, due to their similarities in structure. Nb:SrTiO 3 single crystals are especially attractive as they are highly conductive and therefore can be simultaneously used as substrate and bottom electrode material for the growth of ferroelectric films. Their high conductivity is also very useful for the present investigation. In studies of dielectric ceramics, metal electrodes usually have to be used in electrolysis of water experiments. The electrode effect, particularly the interface effect, may sometimes shadow what hap...

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Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO₃ Ceramics

Lewin

Baeumer

Gunkel

et al. 2018

Adv Funct Materials

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Among the novel materials for electronic applications and novel device concepts beyond classical Si‐based CMOS technology, SrTiO3 represents a prototype role model for functional oxide materials: It enables resistive switching, but can also form a 2D electron gas at its interface and thus enables tunable transistors. However, the interplay between charge carriers and defects in SrTiO3 is still under debate. Infrared spectroscopy offers the possibility to characterize structural and electronic properties of SrTiO3 in operando, but is hampered by the diffraction‐limited resolution. To overcome this limitation and obtain nanoscale IR spectra of donor‐doped Sr1‐xLaxTiO3 ceramics, scattering‐type scanning near‐field optical microscopy is applied. By exploiting plasmon–phonon coupling, the local electronic properties of doped SrTiO3 are quantified from a detailed spectroscopic analysis in the spectral range of the near‐field ‘phonon resonance’. Single crystal‐like mobility, an increase in charge carrier density N and an increase in ε∞ at grain boundaries (µ≈ 5.7 cm2 V−1s−1, N = 7.1 × 1019 cm−3, and ε∞ = 7.7) and local defects (µ≈ 5.4 cm2 V−1s−1, N = 1.3 × 1020 cm−3, and ε∞ = 8.8) are found. In future, subsurface quantification of defects and free charge carriers at interfaces and filaments in SrTiO3 can be envisioned.

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Optical properties of highly reducedSrTiO3−x

Cited by 70 publications

References 22 publications

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

Ambient-temperature incorporated hydrogen in Nb:SrTiO3 single crystals

Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO₃ Ceramics

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Optical properties of highly reducedSrTiO3−x

Cited by 70 publications

References 22 publications

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

Ambient-temperature incorporated hydrogen in Nb:SrTiO3 single crystals

Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics

Contact Info

Product

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Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO₃ Ceramics