Exoelectron emission at phase transitions in BaTiO3

Rosenman, G.; Tomashpolskii, Ju. Ja.; Boǐkova, E. I.; Sevostyanov, M. A.

doi:10.1080/00150198108201985

Cited by 8 publications

(7 citation statements)

References 4 publications

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“…The ferroelectric phase transition is the region where all physical parameters such as structural symmetry, spontaneous polarization, pyroelectric coefficient, dielectric permittivity are changed critically. Anomalous photoemission was observed in monodomain ferroelectric monocrystals BaTiO 3 during all three well-known phase transitions, both in crystals [44][45][46] and thin films. 47 The photostimulated FEE current was asymmetric: The current from the Z ϩ face was almost twice as much as the current from the opposite polar face.…”

Section: Fee During Phase Transitionsmentioning

confidence: 92%

“…The effect was ascribed to two different causes: ͑a͒ band bending of the opposite sign near opposite polar faces and ͑b͒ an asymmetric potential barrier for electrons in ferroelectric crystals during their transport to the emitting surfaces. 48 It should be noted that BaTiO 3 is a high conduc- tive ferroelectric crystal (Ϸ10 Ϫ9 S/cm) and ''dark'' ferroelectric electron emission cannot be observed in these crystals.…”

Section: Fee During Phase Transitionsmentioning

confidence: 99%

“…27 The photoemission yield studied by Boikova and Rosenman 28 gave ⌬Aϭ0.4 eV for LiNbO 3 and ⌬Aϭ0.6 eV for BaTiO 3 . 29 Low ⌬A indicated that the screening charges are localized mainly on surface states with the concentration for LiNbO 3 4ϫ10 14 cm Ϫ2 . 30 The estimated band bending was ⌬ ϩ ϭ0.15 eV and ⌬ Ϫ ϭ0.25 eV and electron affinity ϭ0.25 eV.…”

Section: Expression ͑1͒mentioning

confidence: 99%

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Electron emission from ferroelectrics

Rosenman

Shur

Krasik

et al. 2000

Journal of Applied Physics

312

199

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Electron emission from ferroelectrics ͑FEE͒ is an unconventional electron emission effect. Methods of FEE excitation are quite different compared to classic electron emission from solids. Two kinds of FEE have been observed, ''weak'' and ''strong.'' ''Weak'' electron emission ͑current density 10 Ϫ12-10 Ϫ7 A/cm 2 ͒ occurs from polar surfaces of ferroelectric materials in the ferroelectric phase only. A source of the electric field for ''weak'' FEE excitation is an uncompensated charge, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under a pyroelectric effect, piezoelectric effect, or polarization switching. The FEE is a tunneling emission current which screens uncompensated polarization charges. It is shown that the FEE is an effective tool for direct domain imaging and studies of electronic properties of ferroelectrics. ''Strong'' FEE, which is 10-12 orders of magnitude higher than ''weak'' FEE, achieves 100 A/cm 2 and is plasma-assisted electron emission. Two modes of the surface flashover plasma formation followed by strong electron emission have been studied. The plasma of ferroelectric origin has been observed only in the ferroelectric phase and it is induced by polarization switching or a field-enforced phase transition, such as antiferroelectric-ferroelectric or relaxor-ferroelectric. The second mode of plasma is conventional surface flashover which may be initiated by a high voltage application in any phase from any dielectric, including ferroelectrics. In this review paper we consider numerous experimental results, as well as mechanisms of both types of electron emission from ferroelectrics. The main stress is placed on the material aspect in order to clarify the influence of ferroelectricity ͑ferroelectric phase transitions, polarization switching, etc.͒ on electron emission. Another aspect which is broadly discussed is the potential applications of these unconventional FEE emitters in various devices for development of high density FEE cathodes for microwave devices, as well as FEE converters of IR irradiation into visible light, x-ray imaging, FEE flat panel displays, etc.

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Section: Fee During Phase Transitionsmentioning

confidence: 92%

Section: Fee During Phase Transitionsmentioning

confidence: 99%

Section: Expression ͑1͒mentioning

confidence: 99%

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Electron emission from ferroelectrics

Rosenman

Shur

Krasik

et al. 2000

Journal of Applied Physics

312

199

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“…4 Several authors studied the work function in ferroelectrics. 5 The results were obtained mainly by measurements of the spectral dependence of the photoelectron emission yield 6 and by work function measurements using Kelvin probe. 7 The latter method is based on measuring of the contact potential difference (CPD) between a reference electrode and the sample surface.…”

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confidence: 99%

Kelvin Probe Force Microscopy of Periodic Ferroelectric Domain Structure in KTiOPO₄ Crystals

et al. 2002

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Mono-and periodically poled domain structures of ferroelectric KTiOPO 4 crystals have been studied by Kelvin probe force microscopy. This scanning probe method has allowed us to image the domain structure using a contact potential difference contrast between 180°ferroelectric domains. The measured contact potential difference between adjacent domains showed that the screening in the KTiOPO 4 crystals is provided by the highly mobile potassium ions. The screening charge density distribution and the resulting Debye length near the polar faces have been estimated.

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“…Electron emission during phase transition of BaTiO 3 ceramic samples under vacuum conditions was observed by Kortov and Mints [5] and from γ-irradiated samples of powdered BaTiO 3 by Hayakawa et al [6]. Optically stimulated electron emission during phase transition of BaTiO 3 single crystals grown by Remeika method was reported by Rosenman et al [7,8]. All these experiments were carried out using BaTiO 3 ceramics or single crystals and typical applied voltage of several kV was required to induce the polarization reversal and electron emission from samples in the mm thickness range.…”

Section: Introductionmentioning

confidence: 89%

Low Voltage Electron Emission from BaTiO3 Thin Films Treated in Hydrochloric Acid

Ghemes

Neo

et al. 2008

e-J. Surf. Sci. Nanotechnol.

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Low voltage electron emission from ferroelectric thin films consisting of BaTiO3 is reported. The 1 µm thick BaTiO3 thin films were deposited by spin coating and were annealed to improve their crystallinity. Then surface treatments using hydrochloric acid have been performed and very thin gold top electrodes were deposited. The electron emission capability of these thin films has been tested using a parallel cathode-positively biased anode arrangement in a vacuum chamber at 10 −5 Pa. The turn on electric field for electron emission was 23 V/µm and we obtained an emission charge of about 200 pC/cycle at an electric field of 100 V/µm.

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Exoelectron emission at phase transitions in BaTiO3

Cited by 8 publications

References 4 publications

Electron emission from ferroelectrics

Electron emission from ferroelectrics

Kelvin Probe Force Microscopy of Periodic Ferroelectric Domain Structure in KTiOPO₄ Crystals

Low Voltage Electron Emission from BaTiO3 Thin Films Treated in Hydrochloric Acid

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Exoelectron emission at phase transitions in BaTiO3

Cited by 8 publications

References 4 publications

Electron emission from ferroelectrics

Electron emission from ferroelectrics

Kelvin Probe Force Microscopy of Periodic Ferroelectric Domain Structure in KTiOPO4 Crystals

Low Voltage Electron Emission from BaTiO3 Thin Films Treated in Hydrochloric Acid

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Kelvin Probe Force Microscopy of Periodic Ferroelectric Domain Structure in KTiOPO₄ Crystals