Publisher’s Note: Oxygen Vacancy Clustering and Electron Localization in Oxygen-Deficient<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>LDA</mml:mi><mml:mo>+</mml:mo><mml:mi>U</mml:mi></mml:math>Study [Phys. Rev. Lett.<b>98</b>, 115503 (2007)]

Cuong, Do Duc; Lee, Bora; Choi, Kyeong Mi; Ahn, Hyun Kyong; Han, Seungwu; Lee, Jaichan

doi:10.1103/physrevlett.98.129903

Cited by 71 publications

(104 citation statements)

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“…The oxygen vacancies partially ionize by localizing the conduction electrons and clustering of such vacancies, which is common in STO films grown by PLD, 46 and can act as localizing sites for the itinerant electrons. 47 The randomly distributed and clustered nature of oxygen vacancies in LSTO has been previously reported 14 to influence the phonon transport. Hence it is reasonable that the co-existence of differently reduced regions in the films dictates the observed degenerate electrical conductivity and non-degenerate Seebeck coefficient.…”

Section: B Transport Propertiesmentioning

confidence: 99%

Effect of oxygen vacancy distribution on the thermoelectric properties of La-doped SrTiO3 epitaxial thin films

Kumar

Abutaha

Hedhili

et al. 2012

Journal of Applied Physics

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A detailed study of the role of oxygen vacancies in determining the effective mass and high temperature (300–1000 K) thermoelectric properties of La-doped epitaxial SrTiO3 thin films is presented. It is observed that at intermediate temperatures, a transition from degenerate to non-degenerate behavior is observed in the Seebeck coefficient, but not electrical conductivity, which is attributed to heterogeneous oxygen non-stoichiometry. Heikes formula is found to be invalid for the films with oxygen vacancies. By fitting the spectroscopic ellipsometry (SE) data, obtained in the range 300–2100 nm, using a Drude-Lorentz dispersion relation with two Lorentz oscillators, the electrical and optical properties of the films are extracted. Using the excellent agreement between the transport properties extracted from SE modeling and direct electrical measurements, we demonstrate that an increase in concentration of oxygen vacancies results in a simultaneous increase of both carrier concentration and electron effective mass, resulting in a higher power factor.

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Section: B Transport Propertiesmentioning

confidence: 99%

Effect of oxygen vacancy distribution on the thermoelectric properties of La-doped SrTiO3 epitaxial thin films

Kumar

Abutaha

Hedhili

et al. 2012

Journal of Applied Physics

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“…In this limit, the transport is dominated by the oxygen vacancies, which ionize partially by localizing some of the electrons. Particularly, clusters of oxygen vacancies can act as localizing sites for such itinerant electrons 25,26 and clustering of vacancies is a common feature in PLD grown STO thin films grown under low pressures. 27 In the case of samples containing 15% La, the low temperature resistivity is best described by ρ ∼ sinh 2 ( 1 T ), characteristic of small polaron conduction.…”

Section: B Optical Spectroscopymentioning

confidence: 99%

Tuning the electronic effective mass in double-dopedSrTiO3

et al. 2011

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We elucidate the relationship between effective mass and carrier concentration in an oxide semiconductor controlled by a double doping mechanism. In this model oxide system, Sr1−xLaxTiO 3−δ , we can tune the effective mass ranging from 6-20me as a function of filling (carrier concentration) and the scattering mechanism, which are dependent on the chosen lanthanum and oxygen vacancy concentrations. The effective mass values were calculated from the Boltzmann transport equation using the measured transport properties of thin films of Sr1−xLaxTiO 3−δ . We show that the effective mass decreases with carrier concentration in this large band gap, low mobility oxide and this behavior is contrary to the tradional high mobility, small effective mass semiconductors.

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“…The vacancies either form along a network of extended defects 6 or assemble together to lower the system's energy 7,8 , probably producing large positively charged donor clusters. Another way to more controllably create such a cluster is to "draw" a disc of charge by the atomic force microscope (AFM) tip on the surface of LAO/STO structure with the subcritical thickness for LaAlO 3 (LAO) 9,10 .…”

Section: Introductionmentioning

confidence: 99%

Collapse of electrons to a donor cluster inSrTiO3

Reich

Shklovskiǐ

2015

Phys. Rev. B

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It is known that a nucleus with charge Ze, where Z > 170 creates electron-positron pairs from the vacuum. Electrons collapse onto the nucleus resulting in a net charge Zn < Z while the positrons are emitted. This effect is due to the relativistic dispersion law. The same reason leads to the collapse of electrons to the donor cluster with a large charge number Z in narrow-band gap semiconductors, Weyl semimetals and graphene. In this paper, a similar effect of electron collapse and charge renormalization is found for a donor cluster in SrTiO3 (STO), but with a different origin. At low temperatures, STO has an enormously large dielectric constant and the nonlinear dielectric response becomes dominant when the electric field is still small. This leads to the collapse of electrons into a charged spherical donor cluster with radius R when its total charge number Z exceeds a critical value Zc R/a where a is the lattice constant. The net charge Zne grows with Z until Z exceeds Z * (R/a) 9/7 . After this point, the charge of the compact core Zn remains Z * , while the rest Z * electrons form a sparse Thomas-Fermi electron atmosphere around it. We show that the thermal ionization of such two-scale atoms easily strips the outer atmosphere while the inner core remains preserved. We extend our results to the case of long cylindrical clusters. We discuss how our predictions can be tested by measuring conductivity of chain of discs of charge on the STO surface.

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Publisher’s Note: Oxygen Vacancy Clustering and Electron Localization in Oxygen-DeficientSrTiO3:LDA+UStudy [Phys. Rev. Lett.98, 115503 (2007)]

Cited by 71 publications

References 0 publications

Effect of oxygen vacancy distribution on the thermoelectric properties of La-doped SrTiO3 epitaxial thin films

Effect of oxygen vacancy distribution on the thermoelectric properties of La-doped SrTiO3 epitaxial thin films

Tuning the electronic effective mass in double-dopedSrTiO3

Collapse of electrons to a donor cluster inSrTiO3

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