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Investigation of strain and strain relaxation in functional epitaxial oxides using X-ray scattering techniques

Florine Conchon 1Alexandre Boulle 1René Guinebretière 1Stéphane Pignard 2Cécile Girardot 2Eric Dooryhée 3Jean Louis Hodeau 3Laure Libralesso 4Tien Lin Lee 4

1. Laboratoire Science des Procédés Céramiques et de Traitements de Surface - UMR 6638 CNRS - ENSCI, 47 avenue Albert Thomas, Limoges 87065, France
2. INPG, Laboratoire des Materiaux et du Genie Physique (LMGP), BP 46, Grenoble 38402, France
3. CNRS, Institut Néel (NEEL), 25 rue des Martyrs, Grenoble 38042, France
4. European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France

Abstract

Functional oxide based on the perovskite structure are the subject of intense research in the field of micro- and nanoelectronics. However, in contrast with semiconductor films, oxide layers are much more difficult to grow with a high crystalline quality level which results in very broad and complicated reciprocal space features. Therefore it is often extremely challenging to obtain reliable information concerning the nanostructure of oxide layers using X-ray diffraction (XRD).

In this communication we will adress some important issues that can be encountered in the study of RNiO3 perovskites (R = rare-earth). These compounds are extremely difficult to stabilize because of the less stable 3+ oxidation state of Ni. A possible way to stabilise RNiO3 phases is to use epitaxial strain. It can hence be expected that strain will profoundly affect the structure and microstructure of these epitaxial films.

Using the particular example of SmNiO3 grown on different substrates (SrTiO3, LaAlO3), we will show in this communication that using different complementary X-ray scattering techniques allows us to access a wealth of information concerning the defect structure of the films:

- the contribution of chemical and mechanical effects to the lattice parameter can be rigorously separated using laboratory based X-ray reciprocal space mapping and synchrotron grazing incidence diffraction.

- the effect of relaxation-induced misfit dislocations are investigated using high resolution synchrotron XRD (HRXRD). The presence of misfit dislocations induces asymmetrical longitudinal profiles which are quantitatively analyzed using a semi-kinematical scattering model based on B-spline functions.

- highly localized strain fields due to a particular type of planar faults (Ruddlesden-Popper faults) are studied by HRXRD. These defects give rise to extended diffuse scattering in reciprocal space which can be analyzed using a recently developed phenomenological scattering model.

 

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Presentation: Invited at E-MRS Fall Meeting 2007, Symposium H, by Alexandre Boulle
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-14 18:51
Revised:   2009-06-07 00:44