Hall mobility of undoped n-type conducting strontium titanate single crystals between 19 K and 1373 K

Moos, Ralf; Menesklou, Wolfgang; Härdtl, Karl Heinz

doi:10.1007/bf01540113

Cited by 159 publications

(151 citation statements)

References 12 publications

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“…The reduction of STO in PLD vacuum chambers, however, is not only observed during deposition, but also observed when annealing at physical oxygen pressures below ≈7 · 10 −7 mbar163233, which is in contradiction to the thermodynamic equilibrium measurements performed in chemically controlled gas mixtures or with oxygen pumps232526. To our knowledge, no work sufficiently explained this contradiction between physical oxygen pressure and chemically controlled oxygen pressure so far.…”

mentioning

confidence: 67%

“…1(c)). Remarkably, this carrier concentration corresponds to heavily reduced STO25. To investigate whether the contaminations are responsible for the reduction of STO we varied the duration of the additional pre-annealing step at 400 °C.…”

Section: Reduction Of Sto Substrates During Annealingmentioning

confidence: 99%

“…This can be described by Eq. 1 in the Kröger Vink notation24, reflecting the oxygen pressure dependence of the electron concentration in STO23252627.…”

mentioning

confidence: 99%

“…For high oxygen pressures the concentration of oxygen vacancies is further decreased leading to the formation of holes, eventually resulting in p-conductivity observable at elevated temperatures23252627. This process can be described by Eq.…”

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confidence: 99%

“…This opposes the results of chemically controlled reducing atmosphere annealing experiments (H 2 /Ar/O 2 mixtures), for which the sample is, in opposite to vacuum annealing, under a physical pressure of 1 bar. These experiments determined that STO reduction, in case of inherent acceptor-type impurity content, will only take place at oxygen partial pressures below 10 −17 mbar even at elevated temperatures23252628. The contradiction is often explained by the influence of the laser plume during growth101117.…”

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confidence: 99%

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Unraveling the enhanced Oxygen Vacancy Formation in Complex Oxides during Annealing and Growth

Hensling

Gunkel

et al. 2017

Sci Rep

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The reduction of oxides during annealing and growth in low pressure processes is a widely known problem. We hence investigate the influence of mere annealing and of growth in vacuum systems to shed light on the reasons behind the reduction of perovskites. When comparing the existing literature regarding the reduction of the perovskite model material SrTiO3 it is conspicuous that one finds different oxygen pressures required to achieve reduction for vacuum annealing and for chemically controlled reducing atmospheres. The unraveling of this discrepancy is of high interest for low pressure physical vapor depositions of thin films heterostructures to gain further understanding of the reduction of the SrTiO3. For thermal annealing, our results prove the attached measurement devices (mass spectrometer/ cold cathode gauge) to be primarily responsible for the reduction of SrTiO3 in the deposition chamber by shifting the thermodynamic equilibrium to a more reducing atmosphere. We investigated the impact of our findings on the pulsed laser deposition growth at low pressure for LaAlO3/SrTiO3. During deposition the reduction triggered by the presence of the laser plume dominates and the impact of the measurement devices plays a minor role. During post annealing a complete reoxidization of samples is inhibited by an insufficient supply of oxygen.

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mentioning

confidence: 67%

Section: Reduction Of Sto Substrates During Annealingmentioning

confidence: 99%

“…This can be described by Eq. 1 in the Kröger Vink notation24, reflecting the oxygen pressure dependence of the electron concentration in STO23252627.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Unraveling the enhanced Oxygen Vacancy Formation in Complex Oxides during Annealing and Growth

Hensling

Gunkel

et al. 2017

Sci Rep

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Valence Change Observed by Nanospectroscopy and Spectromicroscopy

Lenser

Dittmann

Strachan

2016

Resistive Switching

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Defect Modulation Doping

Weidner

Fuchs

Bayer

et al. 2019

Adv Funct Materials

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The doping of semiconductor materials is a fundamental part of modern technology, but the classical approaches have in many cases reached their limits both in regard to achievable charge carrier density as well as mobility. Modulation doping, a mechanism that exploits the energy band alignment at an interface between two materials to induce free charge carriers in one of them, is shown to circumvent the mobility restriction. Due to an alignment of doping limits by intrinsic defects, however, the carrier density limit cannot be lifted using this approach. Here, a novel doping strategy using defects in a wide bandgap material to dope the surface of a second semiconductor layer of dissimilar nature is presented. It is shown that by depositing an insulator on a semiconductor material, the conductivity of the layer stack can be increased by 7 orders of magnitude, without the necessity of high-temperature processes or epitaxial growth. This approach has the potential to circumvent limits to both carrier mobility and density, opening up new possibilities in semiconductor device fabrication, particularly for the emerging field of oxide thin film electronics.

show abstract

Hall mobility of undoped n-type conducting strontium titanate single crystals between 19 K and 1373 K

Cited by 159 publications

References 12 publications

Unraveling the enhanced Oxygen Vacancy Formation in Complex Oxides during Annealing and Growth

Unraveling the enhanced Oxygen Vacancy Formation in Complex Oxides during Annealing and Growth

Valence Change Observed by Nanospectroscopy and Spectromicroscopy

Defect Modulation Doping

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