<i>Ab initio</i>study of oxygen-vacancy LaAlO<sub>3</sub>(001) surface

Tang, J.; Zhu, Jun; Wenfeng, Qin; Xiong, Jie; Li, Yanrong

doi:10.1088/1674-1056/17/2/049

Cited by 15 publications

(5 citation statements)

References 30 publications

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“…Ab initio thermodynamical stability diagrams previously calculated for LAO(001) shows that LaOterminated surface is more stable with respect to AlO 2terminated one 57 and LaO-terminated surface containing oxygen vacancy is more stable than oxygen deficient AlO 2 -terminated LAO(001) as well. 58 Mixed surfaces with LaO-and AlO 2 -terminations were not predicted. In fact, our thermodynamic analysis does not support this prediction.…”

Section: Thermodynamic Stabilitymentioning

confidence: 98%

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

et al. 2012

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We present a comprehensive first-principles study of the electronic charge redistribution in atomically sharp LaAlO3/SrTiO3(001) heterointerfaces of both n-and p-types allowing for nonstoichiometric composition. Using two different computational methods within the framework of the density functional theory (linear combination of atomic orbitals and plane waves) we demonstrate that conducting properties of LaAlO3/SrTiO3(001) heterointerfaces strongly depend on termination of LaAlO3(001) surface. We argue that both the "polar catastrophe" and the polar distortion scenarios may be realized depending on the interface stoichiometry. Our calculations predict that heterointerfaces with a non-stoichiometric film-either LaO-terminated n-type or AlO2-terminated p-type-may exhibit the conductivity of n-or p-type, respectively, independently of LaAlO3(001) film thickness.

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Section: Thermodynamic Stabilitymentioning

confidence: 98%

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

et al. 2012

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“…From first principles calculations of ref. 36 the formation energy of an isolated oxygen vacancy at the surface of LAO (in the absence of a field) with reference to oxygen in an isolated molecule (1/2E[O 2 ]), E 0 f,µ=0 , is approx. 6.0 eV.…”

Section: The Surface/interface Chemistry Term Cmentioning

confidence: 99%

Surface defects and conduction in polar oxide heterostructures

2011

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The polar interface between LaAlO3 and SrTiO3 has shown promise as a field effect transistor, with reduced (nanoscale) feature sizes and potentially added functionality over conventional semiconductor systems. However, the mobility of the interfacial two-dimensional electron gas (2DEG) is lower than desirable. Therefore to progress, the highly debated origin of the 2DEG must be understood. Here we present a case for surface redox reactions as the origin of the 2DEG, in particular surface O vacancies, using a model supported by first principles calculations that describes the redox formation. In agreement with recent spectroscopic and transport measurements, we predict a stabilization of such redox processes (and hence Ti 3d occupation) with film thickness beyond a critical value, which can be smaller than the critical thickness for 2D electronic conduction, since the surface defects generate trapping potentials that will affect the interface electron mobility. Several other recent experimental results, such as lack of core level broadening and shifts, find natural explanation. Pristine systems will likely require changed growth conditions or modified materials with a higher vacancy free energy.

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“…With our cleaning procedure, we systematically observed by RHEED and LEED a sharp c (2 × 2) reconstruction 9, 10. This superstructure, never mentioned by other groups, could be related to oxygen vacancies in the LaO terminated plane 13. Even if the atomic model of this reconstruction remains under debate, its observation will ensure us to start the deposit on the same initial surface.…”

Section: Methodsmentioning

confidence: 66%

Si and Ge nanostructures epitaxy on a crystalline insulating LaAlO₃(001) substrate

Bischoff

Mortada

Dentel

et al. 2012

Physica Status Solidi (a)

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We present a comparative structural study of the growth of Si and Ge deposited by molecular beam epitaxy (MBE) on a c(2 × 2) reconstructed LaAlO3(001) substrate. Our findings are based on complementary experimental techniques such as in situ X‐ray photoelectron spectroscopy (XPS), reflection high‐energy electron diffraction (RHEED), low energy electron diffraction (LEED) and ex situ atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). While the layers are amorphous and wet uniformly the substrate in a low deposition temperature range, above 500 °C both Si and Ge growths proceed in a Volmer–Weber (VW) mode leading to the formation of nanocrystals (NCs). The islands are found to be composed of pure Si and Ge and to have abrupt interfaces with the substrate. Both semiconductors (SCs) crystallize in their own diamond structure leading to relaxed NCs. No facets could be observed on the crystalline islands. An epitaxial relationship is established for which the (001) planes of Si and Ge are parallel to the LaAlO3(001) surface but are rotated by 45° around the [001] growth axis. The Ge lattice undergoes a second rotation of 6° with respect to the (001) growth axis. This 6° tilt is an original mechanism to partially compensate the strain in the Ge islands induced by the large misfit. Whereas a unique epitaxial relationship is pointed out for Si NCs, many Ge NCs are randomly orientated on the surface. This is interpreted by the fact that the Ge islands are less anchored to the substrate due to a large misfit and to the fact that the GeO bonds are weaker than the SiO ones.

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Ab initiostudy of oxygen-vacancy LaAlO₃(001) surface

Abstract: Tang Jin-Long( ), Zhu Jun( ) † , Qin Wen-Feng( ), Xiong Jie( ), and Li Yan-Rong( )

Cited by 15 publications

References 30 publications

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

Surface defects and conduction in polar oxide heterostructures

Si and Ge nanostructures epitaxy on a crystalline insulating LaAlO₃(001) substrate

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Ab initiostudy of oxygen-vacancy LaAlO3(001) surface

Abstract: Tang Jin-Long( ), Zhu Jun( ) † , Qin Wen-Feng( ), Xiong Jie( ), and Li Yan-Rong( )

Cited by 15 publications

References 30 publications

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

Surface defects and conduction in polar oxide heterostructures

Si and Ge nanostructures epitaxy on a crystalline insulating LaAlO3(001) substrate

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Product

Resources

About

Ab initiostudy of oxygen-vacancy LaAlO₃(001) surface

Si and Ge nanostructures epitaxy on a crystalline insulating LaAlO₃(001) substrate