Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping

Chen, Yunzhong; Trier, Felix; Wijnands, Tom; Green, R. J.; Gauquelin, Nicolas; Egoavil, Ricardo; Christensen, Dennis Valbjørn; Koster, Gertjan; Huijben, Mark; Bovet, N.; Macke, S.; He, Feizhou; Sutarto, Ronny; Andersen, N.H.; Sulpizio, Joseph; Honig, M.; Prawiroatmodjo, Guenevere E. D. K.; Jespersen, Thomas Sand; Linderoth, Søren; Ilani, Shahal; Verbeeck, Jo; Tendeloo, G. Van; Rijnders, Guus; Sawatzky, G. A.; Pryds, Nini

doi:10.1038/nmat4303

Cited by 188 publications

(232 citation statements)

References 52 publications

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“…This is due to the fact that the bottom of the LMO conduction band is about 1 eV lower than that of STO, any reduction, if occurs, is preferably on the LMO side, i.e. the reconstructed electrons will be firstly transferred to the Mn sublattice before filling the electronic shell of Ti ions 4,26 . Moreover, LMO could activate the oxygen uptaking in STO due to its catalytic activity for oxygen reduction reaction at high temperatures 27 .…”

Section: Introductionmentioning

confidence: 99%

Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

Niu

Gan

Zhang

et al. 2017

Applied Physics Letters

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The two-dimensional electron gas (2DEG) at the non-isostructural interface between spinel γ-Al2O3 and perovskite SrTiO3 is featured by a record electron mobility among complex oxide interfaces in addition to a high carrier density up to the order of 1015 cm−2. Herein, we report on the patterning of 2DEG at the γ-Al2O3/SrTiO3 interface grown at 650 °C by pulsed laser deposition using a hard mask of LaMnO3. The patterned 2DEG exhibits a critical thickness of 2 unit cells of γ-Al2O3 for the occurrence of interface conductivity, similar to the unpatterned sample. However, its maximum carrier density is found to be approximately 3 × 1013 cm−2, much lower than that of the unpatterned sample (∼1015 cm−2). Remarkably, a high electron mobility of approximately 3600 cm2 V−1 s−1 was obtained at low temperatures for the patterned 2DEG at a carrier density of ∼7 × 1012 cm−2, which exhibits clear Shubnikov-de Haas quantum oscillations. The patterned high-mobility 2DEG at the γ-Al2O3/SrTiO3 interface paves the way for the design and application of spinel/perovskite interfaces for high-mobility all-oxide electronic devices.

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Section: Introductionmentioning

confidence: 99%

Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

Niu

Gan

Zhang

et al. 2017

Applied Physics Letters

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“…Nevertheless, these oxygen vacancy dominated 2DELs are characterized by a pronounced carrier freeze out effect, and it remains also challenging to control their formation without a compromise in the properties 16,21,[23][24][25] .…”

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confidence: 99%

“…In this case, the LSMO buffer acts as an electron sink during the formation of interfacial 2DELs, since the partially-filled Mn 3d eg subbands is often lower than the Fermi level of Ti 3d t2g bands. This has led to a charge-transferinduced modulation doping and boosts the 2DEL electron mobility more than 20 times of d-LAO/STO 23 . However, a new puzzle arises, as the total amount of transferred electrons at the d-LAO/LSMO(1uc)/STO interface is found to be approximately 1 e/uc, which is far above the 0.5 e/uc as normally expected by a pure electronic reconstruction scenario considering the polar nature of the buffer layer.…”

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confidence: 99%

Tuning the Two-Dimensional Electron Liquid at Oxide Interfaces by Buffer-Layer-Engineered Redox Reactions

et al. 2017

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“…[6][7][8][9][10][11][12][13] Motivated by interest in quantum phenomena and potential applications, multiple studies have specifically sought to improve the low-temperature electron mobility in LAO/STO interfaces. [13][14][15][16][17][18][19][20][21] In spite of more than a decade of research, the dominant scattering mechanism in LAO/STO interfaces, nonetheless, remains elusive.…”

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confidence: 99%

Universality of electron mobility in LaAlO3/SrTiO3 and bulk SrTiO3

Trier

Reich

Christensen

et al. 2017

Applied Physics Letters

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Metallic LaAlO3/SrTiO3 (LAO/STO) interfaces attract enormous attention, but the relationship between the electron mobility and the sheet electron density, ns, is poorly understood. Here, we derive a simple expression for the three-dimensional electron density near the interface, n3D, as a function of ns and find that the mobility for LAO/STO-based interfaces depends on n3D in the same way as it does for bulk doped STO. It is known that undoped bulk STO is strongly compensated with N≃5×1018 cm−3 background donors and acceptors. In intentionally doped bulk STO with a concentration of electrons n3D<N, background impurities determine the electron scattering. Thus, when n3D<N, it is natural to see in LAO/STO the same mobility as in the bulk. On the other hand, in the bulk samples with n3D>N, the mobility collapses because scattering happens on n3D intentionally introduced donors. For LAO/STO, the polar catastrophe which provides electrons is not supposed to provide an equal number of random donors and thus the mobility should be larger. The fact that the mobility is still the same implies that for the LAO/STO, the polar catastrophe model should be revisited.

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Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping

Cited by 188 publications

References 52 publications

Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

Tuning the Two-Dimensional Electron Liquid at Oxide Interfaces by Buffer-Layer-Engineered Redox Reactions

Universality of electron mobility in LaAlO3/SrTiO3 and bulk SrTiO3

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