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1. Mechanisms of parasitic crystallites formation in ZrB2(0001) buffer layer grown on Si(111)

Author

A. Fleurence, C. Hubault, Yukiko Yamada-Takamura, and W. Zhang

Subjects
Materials science, Silicene, Nucleation, General Physics and Astronomy, Nanotechnology, Surfaces and Interfaces, General Chemistry, Substrate (electronics), Condensed Matter Physics, Epitaxy, Surfaces, Coatings and Films, Chemical physics, Crystallite, Science, technology and society, Anisotropy, Layer (electronics)
Abstract

We present the results of an extensive STM investigation of the parasitic crystallites appearing during the growth of ZrB2(0 0 0 1) buffer layers on Si(1 1 1) aimed at understanding their nature and preventing their growth. Owing to the identification of several of their facets, deemed to induce their nucleation with undesired orientations, we determined the epitaxial relationships with the substrate and pointed out the large variety of possible misorientations. As the short direction of the crystallites systematically corresponds to the largest misfit, the anisotropic epitaxial strain is deduced to be the origin of the anisotropic growth for most of them. We have experimentally demonstrated that the formation of the crystallites can be kinetically prevented giving rise to ZrB2 buffer layers with a dramatically improved quality. This work is therefore expected to open a way to the technologically relevant growth of defect-free GaN-based LED on Si(1 1 1).

Published
2013
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2. Strain effect in PbTiO3/PbZr0.2Ti0.8O3 superlattices: From polydomain to monodomain structures

Author

N. Lemée, M. G. Karkut, C. Hubault, Brice Gautier, Janez Holc, André Perrin, Loic Dupont, Valérie Demange, C. Davoisne, Alexandre Boulle, M. Kosec, Laboratoire de Physique de la Matière Condensée - UR UPJV 2081 (LPMC), Université de Picardie Jules Verne (UPJV), Laboratoire réactivité et chimie des solides - UMR CNRS 7314 (LRCS), Université de Picardie Jules Verne (UPJV)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Axe 3 : organisation structurale multiéchelle des matériaux, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), INL - Dispositifs Electroniques (INL - DE), Institut des Nanotechnologies de Lyon (INL), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Elect Ceramics Department - slovenia, Jozef Stefan Institute [Ljubljana] (IJS), Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Centrale de Lyon (ECL), Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)

Subjects
Diffraction, Materials science, General Physics and Astronomy, 02 engineering and technology, 01 natural sciences, deposition, Mosaicity, Pulsed laser deposition, Optics, Lattice constant, 0103 physical sciences, [CHIM]Chemical Sciences, High-resolution transmission electron microscopy, fields, defects, 010302 applied physics, Condensed matter physics, business.industry, layer, 021001 nanoscience & nanotechnology, Ferroelectric thin films, Reciprocal lattice, Epitaxial multilayers, Volume fraction, X-ray crystallography, 0210 nano-technology, business
Abstract

International audience; Ferroelectric symmetric superlattices consisting of alternating layers of PbTiO3 and PbZr0.2Ti0.8O3, were grown by pulsed laser deposition on SrTiO3 and SrRuO3-coated SrTiO3 substrates. The superlattices, with wavelengths K ranging from 20A ° to 200A ° , were analyzed using x-ray diffraction (h 2h diffraction scans, rocking curves, and reciprocal space mapping), high resolution transmission electron microscopy, and piezoforce scanning microscopy. For large-period superlattices, the strain is relieved by the formation of an a/c polydomain structure which propagates through the whole film. We investigate the influence of the wavelength on the a-domain volume fraction, the lattice parameters, the in-plane strain exx, and the mosaicity of the samples. We show that with decreasing the wavelength, a reduction of the a-domain volume fraction is observed as well as a reduced tensile in-plane strain and a lower mosaicity. A concomitant improvement of the local ferroelectric response is detected. Below a critical wavelength of about 30A ° and a critical sample thickness of 500A ° , the formation of 90 a/c domains is inhibited and the superlattices are completely c oriented. Thus the reduced wavelength induces compressive strain which dominates over the tensile clamping due to the thermal expansion mismatch between the substrate and the superlattice. This compressive strain favors a c-oriented structure in the PbTiO3/PbZr0.2Ti0.8O3 superlattices.

Published
2012
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3. Inhibition of polydomain formation in PbTiO3/PbZr0.2Ti0.8O3 superlattices by intercalation of ultra-thin SrTiO3 layers

Author

Alexandre Boulle, C. Hubault, N. Lemée, M. G. Karkut, Janez Holc, C. Davoisne, M. Kosec, André Perrin, Loic Dupont, Laboratoire de Physique de la Matière Condensée - UR UPJV 2081 (LPMC), Université de Picardie Jules Verne (UPJV), Laboratoire réactivité et chimie des solides - UMR CNRS 7314 (LRCS), Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Axe 3 : organisation structurale multiéchelle des matériaux, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Elect Ceramics Department - slovenia, Jozef Stefan Institute [Ljubljana] (IJS), Université de Picardie Jules Verne (UPJV)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, superlattices, Physics and Astronomy (miscellaneous), Superlattice, Intercalation (chemistry), 02 engineering and technology, 01 natural sciences, Zirconium compounds, epitaxial layers, Pulsed laser deposition, 0103 physical sciences, transmission electron microscopy, lead compounds, [CHIM]Chemical Sciences, Elasticity (economics), 010306 general physics, Polarization (electrochemistry), pulsed laser deposition, Condensed matter physics, association, 021001 nanoscience & nanotechnology, Crystallography, Reciprocal lattice, Transmission electron microscopy, zirconium compounds, elasticity, 0210 nano-technology
Abstract

International audience; We used pulsed laser deposition to grow a series of PbTiO3/PbZr0.2Ti0.8O3 superlattices on SrTiO3 and SrRuO3/SrTiO3 substrates. An a/c polydomain structure was evidenced by reciprocal space mapping and by transmission electron microscopy. Insertion of ultra-thin layers of SrTiO3 at the interfaces between PbTiO3 and PbZr0.2Ti0.8O3 layers has inhibited this polydomain formation. A strong decrease in the tetragonality indicates clearly that the polarization state in these superlattices has changed due to the insertion of the SrTiO3 layers. A purely elastic mechanism does not seem to explain the determined structural parameters

Published
2011
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4. Polarization Rotation in Ferroelectric Tricolor PbTiO3/SrTiO3/PbZr0.2Ti0.8O3 Superlattices.

Author

Lemée N, Infante IC, Hubault C, Boulle A, Blanc N, Boudet N, Demange V, and Karkut MG

Abstract

In ferroelectric thin films, controlling the orientation of the polarization is a key element to controlling their physical properties. We use laboratory and synchrotron X-ray diffraction to investigate ferroelectric bicolor PbTiO3/PbZr0.2Ti0.8O3 and tricolor PbTiO3/SrTiO3/PbZr0.2Ti0.8O3 superlattices and to study the role of the SrTiO3 layers on the domain structure. In the tricolor superlattices, we demonstrate the existence of 180° ferroelectric stripe nanodomains, induced by the depolarization field produced by the SrTiO3 layers. Each ultrathin SrTiO3 layer modifies the electrostatic boundary conditions between the ferroelectric layers compared to the corresponding bicolor structures, leading to the suppression of the a/c polydomain states. Combined with the electrostatic effect, the tensile strain induced by PbZr0.2Ti0.8O3 in the PbTiO3 layers leads to polarization rotation in the system as evidenced by grazing incidence X-ray measurements. This polarization rotation is associated with the monoclinic Mc phase as revealed by the splitting of the (HHL) and (H0L) reciprocal lattice points. This work demonstrates that the tricolor paraelectric/ferroelectric superlattices constitute a tunable system to investigate the concomitant effects of strains and depolarizing fields. Our studies provide a pathway to stabilize a monoclinic symmetry in ferroelectric layers, which is of particular interest for the enhancement of the piezoelectric properties.

Published
2015
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