Paper SA+2D+AC+AS+TF-TuM2
A Versatile Method for the Fabrication of 2D-electron Systems at Functional Oxide Surfaces
Tuesday, November 8, 2016, 8:20 am, Room 103C
| Session: |
Applications of Synchrotron-based Techniques to 2D Materials (8:00-10:00 am)/Complex Functional Materials and Heterostructures (11:00 am-12:20 pm) |
| Presenter: |
Patrick Le Fèvre, Synchrotron SOLEIL, France |
| Authors: |
T.C. Rödel, Université Paris-Sud - SOLEIL, France
P. Le Fèvre, Synchrotron SOLEIL, France
F. Fortuna, Université Paris-Sud - IN2P3, France
E. Frantzeskakis, Université Paris-Sud - IN2P3, France
F. Bertran, Synchrotron SOLEIL, France
T. Maroutian, Université Paris-Sud - CNRS, France
P. Lecoeur, Université Paris-Sud - CNRS, France
B. Mersey, Université de Caen, France
A.F. Santander-Syro, Université Paris-Sud - IN2P3, France
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| Correspondent: |
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A critical challenge of modern materials science is to tailor novel states of matter suitable for future applications beyond semiconductor technology. In this prospect, 2D electron systems (2DESs), analogous to those created in semiconductors heterostructures, have been observed at the LaAlO3/SrTiO3 interface [1] and show amazing physical properties like metal-to-insulator transitions, superconductivity or magnetism. It was then demonstrated that 2DES could also be stabilized at the surface of SrTiO3 [2] or other oxides [3], although it requires the use of intense UV or X-ray synchrotron radiation to desorb oxygen from the surface and dope it with electrons. This opened the way for the use of surface sensitive techniques, like Angle-Resolved PhotoEmission spectroscopy (ARPES) which provided a clear description of the microscopic electronic structure of the quantum well states. However, 2DESs at oxygen-deficient surfaces can be only manipulated and studied in ultra-high vacuum (to preserve the O-vacancies from re-oxidation) and thus, are not suited for experiments or applications at ambient conditions. Here we demonstrate a new, versatile and cost-effective method to generate passivated 2DESs on large areas of UHV-prepared functional oxide surfaces. It consists in a simple evaporation at room temperature of an aluminum film onto the oxide surface. Aluminum acts as a reducing agent and pumps oxygen from the substrate. It oxidizes into an insulating AlOx layer, protecting an underlying homogeneous 2DES confined in the first atomic planes of the oxide substrate. 2 Å of Al are sufficient to create a saturated 2DES on differently oriented surfaces of SrTiO3, anatase-TiO2, or BaTiO3, which were all studied by ARPES to determine the band structure (effective mass, orbital order and charge carrier densities) [4].[1] A. Ohtomo, H. Y. Hwang, Nature 427, 423 (2004).
[2] A. F. Santander-Syro, O. Copie, T. Kondo, F. Fortuna, S. Pailhes, R. Weht, X. G. Qiu, F. Bertran, A. Nicolaou, A. Taleb-Ibrahimi, P. Le Fèvre, G. Herranz, M. Bibes, N. Reyren, Y. Apertet, P. Lecoeur, A. Barthélémy, M. J. Rozenberg, Nature 469, 189 (2011).
[3] T. C. Rödel, F. Fortuna, F. Bertran, M. Gabay, M. J. Rozenberg, A. F. Santander-Syro, and P. Le Fèvre, Phys. Rev. B 92, 041106 (2015).
[4] T. C. Rödel, F. Fortuna, S. Sengupta, E. Frantzeskakis, P. Le Fèvre, F. Bertran, B. Mercey, S. Matzen, G. Agnus, T. Maroutian, P. Lecœur, and A. F. Santander-Syro, Adv. Mater. 28, 1976 (2016).