Defect chemistry of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mi>n</mml:mi></mml:mrow></mml:math>junctions in complex oxides

Saraf, Shimon; Markovich, Miri; Rothschild, Avner

doi:10.1103/physrevb.82.245208

Cited by 18 publications

(13 citation statements)

References 36 publications

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“…[ 9 ] (3 of 9) 1500368 wileyonlinelibrary.com within the range of the expected work function of Nb:STO whose electron affi nity is reported to be ≈4 eV. [ 19 ] This simplifi cation is justifi ed since, according to previous calculations, [ 11 ] most of the space charge region in a similar Fe:STO/Nb:STO junction falls in the Fe-doped side of the junction. It enables modeling the junction as an MIM structure, [ 20 ] wherein the insulator corresponds to the Fe:STO layer.…”

Section: Evmentioning

confidence: 90%

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Parallel Band and Hopping Electron Transport in SrTiO₃

Saraf

Riess

Rothschild

2016

Adv Elect Materials

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SrTiO3 (STO) is a model system for studying oxide electronic devices. This work examines the electronic transport through a heterostructure comprising an acceptor (Fe)‐doped STO layer on a donor (Nb)‐doped STO substrate. This is done by fitting the steady‐state current–voltage (I–V) curve measured at ambient temperature to numerical solutions of the drift‐diffusion equations of itinerant (i.e., free) electrons and holes (band conduction) and localized electrons hopping through defect states within the bandgap (hopping conduction). The analysis shows that at reverse bias and small forward bias the current is carried mostly by hopping electrons that give rise to unexpectedly high currents. At forward bias above 1 V, most of the current is due to electron transport through the conduction band. The transition from hopping to band conduction occurs when the quasi Fermi levels of electrons and holes depart from the energy level of the defect states through which the electrons hop. These observations shed new light on the transport properties of STO‐based devices at ambient temperatures wherein ionic defects such as oxygen vacancies are immobile and holes are trapped, for the most part.

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Section: Evmentioning

confidence: 90%

“…Similar results were reported by us in the past. [ 11 ] Thus Fe:STO thin fi lms in contact with Nb:STO substrates are inverted to an n -type semiconductor close to the substrate, despite the Fe acceptor doping. This explains why the itinerant hole concentration and the respective current are negligible.…”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

Parallel Band and Hopping Electron Transport in SrTiO₃

Saraf

Riess

Rothschild

2016

Adv Elect Materials

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“…The same situation could be observed for the case of extrinsic doping, where there will be a sensitive balance between electronic and ionic disorder. [48][49][50] Thus, we have demonstrated that while complexation of oppositely charged defect centers is not anticipated in SrTiO 3 or other perovskite materials with high dielectric constants, the presence of stoichiometric defects can affect the fundamental thermodynamic quantities associated with ion transport. The interactions between point defects have a…”

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confidence: 89%

Strontium migration assisted by oxygen vacancies in SrTiO3from classical and quantum mechanical simulations

et al. 2011

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“…1 have been recognized in literature, but were usually treated separately with different modeling methods. For example, numerical implementations considered either only the band offset, [21][22][23] or only the drift-diffusion, [24][25][26] or only the segregation energy, [27][28][29][30][31] or the band offset and segregation energy at a semiconductor heterojunction, 32,33 or the chemical potential difference and segregation energy at a grain boundary. [18][19][20][34][35][36] In the rest of this section, we provide more details on these numerical implementations from literature.…”

Section: Introductionmentioning

confidence: 99%

“…Ionic and electronic drift-diffusion models based on the chemical potential difference (factor (b)) have been built for mixed electronic-ionic pn homojunctions made of p-type and n-type doped SrTiO 3 . 24 Similar continuum level studies have also been implemented for a metal/oxide interface 29 and a gas/oxide interface 26 based on first-principle predictions. However, in these two systems the segregation energy term (factor (c)) is still missing from the consideration of the charged point defect redistribution.…”

Section: Introductionmentioning

confidence: 99%

Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO₂/Cr₂O₃

Yang

Youssef

Yildiz

2017

Phys. Chem. Chem. Phys.

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We present a multi-scale approach to predict equilibrium defect concentrations across oxide/oxide hetero-interfaces. There are three factors that need to be taken into account simultaneously for computing defect redistribution around the hetero-interfaces: the variation of local bonding environment at the interface as epitomized in defect segregation energies, the band offset at the interface, and the equilibration of the chemical potentials of species and electrons via ionic and electronic drift-diffusion fluxes. By including these three factors from the level of first principles calculation, we build a continuum model for defect redistribution by concurrent solution of Poisson's equation for the electrostatic potential and the steady-state equilibrium drift-diffusion equation for each defect. This model solves for and preserves the continuity of the electric displacement field throughout the interfacial core zone and the extended space charge zones. We implement this computational framework to a model hetero-interface between the monoclinic zirconium oxide, m-ZrO, and the chromium oxide CrO. This interface forms upon the oxidation of zirconium alloys containing chromium secondary phase particles. The model explains the beneficial effect of the oxidized Cr particles on the corrosion and hydrogen resistance of Zr alloys. Under oxygen rich conditions, the ZrO/CrO heterojunction depletes the oxygen vacancies and the sum of electrons and holes in the extended space charge zone in ZrO. This reduces the transport of oxygen and electrons thorough ZrO and slows down the metal oxidation rate. The enrichment of free electrons in the space charge zone is expected to decrease the hydrogen uptake through ZrO. Moreover, our analysis provides a clear anatomy of the components of interfacial electric properties; a zero-Kelvin defect-free contribution and a finite temperature defect contribution. The thorough analytical and numerical treatment presented here quantifies the rich coupling between defect chemistry, thermodynamics and electrostatics which can be used to design and control oxide hetero-interfaces.

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Defect chemistry ofpnjunctions in complex oxides

Cited by 18 publications

References 36 publications

Parallel Band and Hopping Electron Transport in SrTiO₃

Parallel Band and Hopping Electron Transport in SrTiO₃

Strontium migration assisted by oxygen vacancies in SrTiO3from classical and quantum mechanical simulations

Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO₂/Cr₂O₃

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Defect chemistry ofpnjunctions in complex oxides

Cited by 18 publications

References 36 publications

Parallel Band and Hopping Electron Transport in SrTiO3

Parallel Band and Hopping Electron Transport in SrTiO3

Strontium migration assisted by oxygen vacancies in SrTiO3from classical and quantum mechanical simulations

Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO2/Cr2O3

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Product

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Parallel Band and Hopping Electron Transport in SrTiO₃

Parallel Band and Hopping Electron Transport in SrTiO₃

Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO₂/Cr₂O₃