Conduction-band edge and Shubnikov–de Haas effect in low-electron-density SrTiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>

Allen, S. J.; Jalan, Bharat; Lee, SungBin; Ouellette, Daniel G.; Khalsa, Guru; Jaroszyński, J.; Stemmer, Susanne; MacDonald, Allan H.

doi:10.1103/physrevb.88.045114

Cited by 63 publications

(84 citation statements)

References 35 publications

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“…The theoretically predicted spacing for these two subbands ranges between $160 and 270 meV for a carrier density of $3 Â 10 14 cm À2 , 14,16,18,19,21,42 i.e., the density of the bottom 2DEG. The larger subband spacing in the experiments may be due to a larger confinement (out-of-plane) mass than is commonly assumed in theory, 44 and/or the compressive in-plane epitaxial strain from the lattice mismatch with the LSAT substrate, which lowers the energy of the d xy subbands, 45,46 Considering this, experiments and theory are in excellent agreement.…”

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confidence: 69%

Subband structure of two-dimensional electron gases in SrTiO3

Raghavan

Allen

Stemmer

2013

Applied Physics Letters

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Tunneling between two parallel, two-dimensional electron gases (2DEGs) in a complex oxide heterostructure containing a large, mobile electron density of ~ 3x10^14 cm^-2 is used to probe the subband structure of the 2DEGs. Temperature-dependent current-voltage measurements are performed on SrTiO3/GdTiO3/SrTiO3 junctions, where GdTiO3 serves as the tunnel barrier, and each interface contains a high-density 2DEG. Resonant tunneling features in the conductance and its derivative occur when subbands on either side of the barrier align in energy as the applied bias is changed, and are used to analyze subband energy spacings in the two 2DEGs. We show that the results agree substantially with recent theoretical predictions for such interfaces.Comment: Submitted to Appl. Phys. Let

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confidence: 69%

Subband structure of two-dimensional electron gases in SrTiO3

Raghavan

Allen

Stemmer

2013

Applied Physics Letters

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“…Electron mobility and other transport properties depend crucially on the conduction-band structure of STO, which has already been investigated in a number of studies. [3][4][5] Still, a clear understanding of the transport properties of STO has not yet been established.…”

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First-principles study of the mobility ofSrTiO3

et al. 2014

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We investigate the electronic and vibrational spectra of SrTiO3, as well as the coupling between them, using first-principles calculations. We compute electron-phonon scattering rates for the three lowest-energy conduction bands and use Boltzmann transport theory to calculate the room-temperature mobility of SrTiO3. The results agree with experiment and highlight the strong impact of longitudinal optical phonon scattering. Our analysis provides important insights into the key factors that determine room temperature mobility, such as the number of conduction bands and the nature and frequencies of longitudinal phonons. Such insights provide routes to engineering materials with enhanced mobilities.There is great interest in using SrTiO 3 (STO) as a wide-band-gap semiconductor in novel electronic devices. Thanks to recent progress in epitaxial growth of STO, 1 n-doped films have been achieved with carrier mobility as high as 53,0002 However, roomtemperature mobilities are orders of magnitude smaller, around a few cm 2 V −1 s −1 , potentially forming a significant limitation in electronic device applications 1 and lending urgency to the investigation of the key material parameters that affect electron transport. Electron mobility and other transport properties depend crucially on the conduction-band structure of STO, which has already been investigated in a number of studies.3-5 Still, a clear understanding of the transport properties of STO has not yet been established.Transport properties, conduction mechanisms, and the dependence of mobility on temperature and electron density of STO have been investigated both in single crystal 6 and epitaxially grown samples.7 Recent experiments based on the measurement of Shubnikov de Haas oscillations 3,4 in STO thin films yielded effective band masses that are significantly larger than those obtained from band-structure calculations.8 The mass enhancement was attributed to the strong electron-phonon coupling in STO.3,4 The effect of electron-phonon interactions has also been discussed in relation to electron mobility. Typically, the rapid decrease of the electron mobility with increasing temperature has been associated with scattering of conduction electrons by polar optical phonon modes.9,10 Consequences of electron-phonon scattering on the effective mass of electrons in the conduction bands have been studied by analyzing the spectral weight of the experimental optical conductivity 11 and within the context of large-polaron models.12 More recently, the effect of electron-phonon scattering over a wide temperature range has been investigated for thin films.7 An analysis based on phenomenological models is consistent with longitudinal optical (LO) phonon scattering determining the room-temperature mobility, while at lower temperatures (between 2 and 200 K), transverse optical (TO) modes were also found to be important.Here we investigate the vibrational and electronic spectra of STO, as well as their coupling. We find that polar optical mode scattering leads to low mobilities ...

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“…where h is the reduced Planck's constant, e is the electron charge, k B is the Boltzmann constant, hx LO is the energy of the LO phonon, b is the electron-phonon coupling constant, m e is the electron effective mass (taken to be 1.8 times the free electron mass 29 ), m P ¼ m e ð1 þ b=6Þ is the polaron mass, and f ðbÞ is a function with a value of approximately one. 28 K LO is approximately 0.12 eV cm 2 /V s, see Ref.…”

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Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO3

Mikheev

Himmetoḡlu

Kajdos

et al. 2015

Applied Physics Letters

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We analyze and compare the temperature dependence of the electron mobility of two- and three-dimensional electron liquids in SrTiO3. The contributions of electron-electron scattering must be taken into account to accurately describe the mobility in both cases. For uniformly doped, three-dimensional electron liquids, the room temperature mobility crosses over from longitudinal optical (LO) phonon-scattering-limited to electron-electron-scattering-limited as a function of carrier density. In high-density, two-dimensional electron liquids, LO phonon scattering is completely screened and the mobility is dominated by electron-electron scattering up to room temperature. The possible origins of the observed behavior and the consequences for approaches to improve the mobility are discussed.

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Conduction-band edge and Shubnikov–de Haas effect in low-electron-density SrTiO3

Abstract: The Shubnikov-de Haas effect is used to explore the conduction band edge of high mobility

Cited by 63 publications

References 35 publications

Subband structure of two-dimensional electron gases in SrTiO3

Subband structure of two-dimensional electron gases in SrTiO3

First-principles study of the mobility ofSrTiO3

Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO3

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