Origin of Metallic States at the Heterointerface between the Band Insulators<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>LaAlO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>and<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>

Yoshimatsu, K.; Yasuhara, Ryo; Kumigashira, Hiroshi; Oshima, Masaharu

doi:10.1103/physrevlett.101.026802

Cited by 166 publications

(133 citation statements)

References 23 publications

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“…The discovery of a 2DEG (ref. 3) at the heterointerface between band insulators LaAlO 3 (LAO) and SrTiO 3 (STO) has launched many experimental [2][3][4][5][6][7][8][9][10][11][12]16 and theoretical 13,17,18 investigations of the fundamental origins and properties of this novel electronic state. Thiel et al 7 reported non-volatile electrical control of a metal-insulator quantum phase transition in LAO/STO heterointerface at room temperature.…”

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confidence: 99%

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Creation of a two-dimensional electron gas at an oxide interface on silicon

et al. 2010

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In recent years, reversible control over metal-insulator transition has been shown, at the nanoscale, in a two-dimensional electron gas (2DEG) formed at the interface between two complex oxides. These materials have thus been suggested as possible platforms for developing ultrahigh-density oxide nanoelectronics. A prerequisite for the development of these new technologies is the integration with existing semiconductor electronics platforms. Here, we demonstrate room-temperature conductivity switching of 2DEG nanowires formed at atomically sharp LaAlo 3 /srTio 3 (LAo/sTo) heterointerfaces grown directly on (001) silicon (si) substrates. The room-temperature electrical transport properties of LAo/sTo heterointerfaces on si are comparable with those formed from a srTio 3 bulk single crystal. The ability to form reversible conducting nanostructures directly on si wafers opens new opportunities to incorporate ultrahigh-density oxide nanoelectronic memory and logic elements into well-established si-based platforms.

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“…H eterointerfaces between different oxide layers can display remarkable electrical properties 1 that differ from either constituent, such as a two-dimensional electron gas (2DEG, refs [2][3][4][5][6][7][8][9][10][11][12][13][14] and interfacial superconductivity 15 . The discovery of a 2DEG (ref.…”

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Creation of a two-dimensional electron gas at an oxide interface on silicon

et al. 2010

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“…These data also suggest that many of the conflicting (and often contradictory) studies of this popular system can be explained by this observation, that is, whether measurements are made in situ 31 , or after various surface exposures (for example, atmospheric water, or solvent cleaning) [32][33][34] , the sensitive electronic structure of the interface may be dramatically altered. For example, the predicted electric field across the LaAlO 3 layer [18][19][20] was not observed in X-ray photoemission studies 32 that may be explained consistently because the surface adsorbates (in particular atmospheric water) induced by the ex-situ processing reduce V Uncom , or equally, the electrical field across the LaAlO 3 layer.…”

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confidence: 94%

Control of electronic conduction at an oxide heterointerface using surface polar adsorbates

et al. 2011

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The interface between LaAlo 3 and srTio 3 possesses a range of intriguing properties, notably a proposed connection between the surface state of the LaAlo 3 and the conductivity buried in the srTio 3 . Here we study the effect of the surface adsorption of a variety of common laboratory solvents on the conductivity at the interface between LaAlo 3 and srTio 3 . We show that the application of chemicals such as acetone, ethanol, and water can induce a large change in the conductivity, and, in particular, an insulator to metal transition around the critical LaAlo 3 thickness. This phenomenon is observed only for polar solvents. These data provide experimental evidence for a general polarization-facilitated electronic transfer mechanism.

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“…The resulting bound charges would give rise to a finite electric field and confining potential at the interface. 27,46,47 This is analogous to the mechanism that gives rise to a confined electron gas in wide bandgap polar GaN (III-V) and ZnO (II-VI) based heterostructures. 3,4 Thus the weak polarity of the SrTiO 3 may also play an important role in determining the electrostatic boundary conditions at the LaAlO 3 /SrTiO 3 interface, in direct comparison with the polar semiconductors.…”

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Built-in and induced polarization across LaAlO3/SrTiO3 heterojunctions

et al. 2010

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Ionic crystals terminated at oppositely charged polar surfaces are inherently unstable and expected to undergo surface reconstructions to maintain electrostatic stability. Essentially, an electric field that arises between oppositely charged atomic planes gives rise to a built-in potential that diverges with thickness. Here we present evidence of such a built-in potential across polar LaAlO3 thin films grown on SrTiO3 substrates, a system well known for the electron gas that forms at the interface. By performing tunneling measurements between the electron gas and metallic electrodes on LaAlO3 we measure a built-in electric field across LaAlO3 of 80.1 meV/Å. Additionally, capacitance measurements reveal the presence of an induced dipole moment across the heterostructure. We forsee use of the ionic built-in potential as an additional tuning parameter in both existing and novel device architectures, especially as atomic control of oxide interfaces gains widespread momentum.As dictated by Maxwell's equations, the accumulation of screening charges at the boundary between dissimilar materials is one means 1 of ensuring a continuous electric displacement at the interface. 2 For instance, a layer of trapped screening charge forms the two dimensional electron gas that compensates a polarization mismatch at gallium nitride 3 and zinc oxide 4 based heterostructure interfaces. In insulating oxides, charge accumulation was observed at the interface between SrTiO 3 substrates with atomically precise surfaces and polar LaAlO 3 films. 5 LaAlO 3 thin films grown on singly terminated SrTiO 3 surfaces 6 comprise negatively charged AlO 2 and positively charged LaO end planes and are polar in the ionic limit. 1,7,8 When at least four unit cells (u.c.) of LaAlO 3 are deposited on TiO 2 terminated SrTiO 3 , an electron gas forms near the interface in SrTiO 3 . 5,9,10 It is often hypothesized that at a thickness of four u.c. the potential across LaAlO 3 exceeds the band gap of SrTiO 3 and electrons tunnel from the valence band of LaAlO 3 to the SrTiO 3 potential well, completely diminishing the potential across LaAlO 3 . 11 Thus within this picture, in the presence of an electron gas no field would be expected across the LaAlO 3 . However, if all the charge carriers do not lie precisely at the interface or have an extrinsic (oxygen vacancies 12 or cation doping 13 ) origin, the LaAlO 3 potential will not be fully screened and can thus be probed. 14 Alternatively, the precise band alignment between the LaAlO 3 and SrTiO 3 will also determine the strength of the residual fields in the LaAlO 3 . 15 Addressing this issue by determining the existence of an uncompensated built-in potential in LaAlO 3 is central to understanding the true nature of the polar LaAlO 3 /SrTiO 3 interface.We probe the potential landscape across the LaAlO 3 and the interface region in SrTiO 3 by employing a typical metal-insulator-metal capacitor geometry such that the LaAlO 3 thin films form the dielectric layer sandwiched between evaporated metallic electrodes an...

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Origin of Metallic States at the Heterointerface between the Band InsulatorsLaAlO3andSrTiO3

Cited by 166 publications

References 23 publications

Creation of a two-dimensional electron gas at an oxide interface on silicon

Creation of a two-dimensional electron gas at an oxide interface on silicon

Control of electronic conduction at an oxide heterointerface using surface polar adsorbates

Built-in and induced polarization across LaAlO3/SrTiO3 heterojunctions

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