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34 results on '"Derivaz, M."'

1. Structure of germanene/Al(111): a two-layers surface alloy

Author

Zhang, K., Sciacca, D., Hanf, M. -C., Bernard, R., Borensztein, Yves, Resta, A., Garreau, Y., Vlad, A., Coati, A., Lefebvre, I., Derivaz, M., Pirri, C., Sonnet, P., Stephan, R., and Prévot, G.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Unlike silicene, for which the demonstration of its existence has been done through numerous independent studies, the possibility of growing epitaxial germanene remains highly controversial. It has been recently shown by scanning tunneling microscopy that the (3 x 3) surface reconstruction formed upon Ge deposition on Al(111) presents a honeycomb structure, and it was assigned to a pure germanene monolayer. Using quantitative measurements by surface X-ray diffraction compared to density functional theory calculations, we demonstrate that this Ge/Al(111) (3 x 3) reconstruction corresponds, in fact, to a mixed Ge--Al honeycomb layer on top of an alloyed interfacial layer. The model of a germanene monolayer on top of the Al(111) surface can be completely excluded.

Published
2021

2. Resolving the structure of the striped Ge layer on Ag(111): Ag$_2$Ge surface alloy with alternate fcc and hcp domains

Author

Zhang, K., Sciacca, D., Coati, A., Bernard, R., Borensztein, Yves, Diener, P., Grandidier, B., Lefebvre, I., Derivaz, M., Pirri, C., and Prévot, Geoffroy

Subjects
Condensed Matter - Materials Science
Abstract

Two-dimensional (2D) honeycomb lattices beyond graphene, such as germanene, promise new physical properties such as quantum spin Hall effect. While there have been many claims of growth of germanene, the lack of precise structural characterization of the epitaxial layers synthesized hinders further research. The striped layer formed by Ge deposition on Ag(111) has been recently ascribed as a stretched germanene layer. Using surface X-ray diffraction and density functional theory calculations, we demonstrate that it corresponds in fact to a Ag$_2$Ge surface alloy with an atomic density 6.45% higher than the Ag(111) atomic density. The overall structure is formed by stripes associated with a face-centered cubic top-layer alignment, alternating with stripes associated with an hexagonal-close-packed top-layer alignment, in great analogy with the ($22\times\sqrt3$) Au(111) reconstruction.

Published
2021
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4. Combined surface x-ray diffraction and density functional theory study of the germanene/Al(111)- (7×7)R19.1∘ structure

Author

Zhang, K., primary, Hanf, M.-C., additional, Sciacca, D., additional, Bernard, R., additional, Borensztein, Y., additional, Resta, A., additional, Garreau, Y., additional, Vlad, A., additional, Coati, A., additional, Lefebvre, I., additional, Derivaz, M., additional, Pirri, C., additional, Sonnet, P., additional, Stephan, R., additional, and Prévot, G., additional

Published
2022
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7. Combined surface x-ray diffraction and density functional theory study of the germanene/Al(111)-(7×7) R19.1° structure

Author

Zhang, K., Hanf, M.C., Sciacca, D., Bernard, Romain, Borensztein, Yves, Resta, A., Garreau, Y., Vlad, A., Coati, A., Lefebvre, Isabelle, Derivaz, M., Pirri, C., Sonnet, P., Stephan, R., Prévot, G., Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Science des Matériaux de Mulhouse (IS2M), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Physique - IEMN (PHYSIQUE - IEMN), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), This study is financially supported the French National Research Agency (Germanene Project No. ANR-17-CE09-0021-03). K.Z. is supported by the Chinese Scholarship Council (CSC Contract No. 201808070070). The authors would like to acknowledge the High Performance Computing Center of the University of Strasbourg for supporting this work by providing scientific support and access to computing resources. Part of the computing resources were funded by the Equipex Equip@Meso project (Programme Investissements d’Avenir) and the CPER Alsacalcul/Big Data., ANR-17-CE09-0021,GERMANENE,Croissance de germanene sur substrats à bande interdite(2017), and ANR-10-EQPX-0029,EQUIP@MESO,Equipement d'excellence de calcul intensif de Mesocentres coordonnés - Tremplin vers le calcul petaflopique et l'exascale(2010)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics
Abstract

International audience; Several studies have reported the possible growth of germanene on various metal surfaces. However, the exact structure of the layers formed upon evaporation at or above room temperature remains controversial. In particular, the layers obtained after Ge deposition on Al(111) have been either considered as honeycomb organization of Ge atoms on top of a nonreconstructed substrate, or as alloyed layers. Using quantitative measurements by surface x-ray diffraction compared to density functional theory calculations, we show that the (√7×√7)R±19.1∘ reconstruction obtained after room temperature deposition is a mixed Ge-Al honeycomb layer, on top of an Al(111) plane, and not a pure germanene layer.

Published
2022

8. Resolving the structure of the striped Ge layer on Ag ( 111 ) : Ag 2 Ge surface alloy with alternate fcc and hcp domains

Author

Zhang, K., Sciacca, D., Coati, A., Bernard, R., Borensztein, Yves, Diener, P., Grandidier, B., Lefebvre, Isabelle, Derivaz, M., Pirri, C., Prévot, Geoffroy, Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Physique - IEMN (PHYSIQUE - IEMN), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Institut des Biomolécules Max Mousseron [Pôle Chimie Balard] (IBMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Science des Matériaux de Mulhouse (IS2M), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Chinese Scholarship Council (CSC Contract No. 201808070070), This study is financially supported by the French National Research Agency (Germanene Project No. ANR-17-CE09-0021-03), Renatech Network, PCMP PCP, ANR-17-CE09-0021,GERMANENE,Croissance de germanene sur substrats à bande interdite(2017), Borensztein, Yves, Croissance de germanene sur substrats à bande interdite - - GERMANENE2017 - ANR-17-CE09-0021 - AAPG2017 - VALID, Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, and Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)

Subjects
[PHYS.COND.CM-GEN] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience; Two-dimensional (2D) honeycomb lattices beyond graphene, such as germanene, promise new physical properties such as quantum spin Hall effect. While there have been many claims of growth of germanene, the lack of precise structural characterization of the epitaxial layers synthesized hinders further research. The striped layer formed by Ge deposition on Ag(111) has been recently ascribed as a stretched germanene layer. Using surface X-ray diffraction and density functional theory calculations, we demonstrate that it corresponds in fact to a Ag2Ge surface alloy with an atomic density 6.45% higher than the Ag(111) atomic density. The overall structure is formed by stripes associated with a face-centered cubic top-layer alignment, alternating with stripes associated with an hexagonal-close-packed top-layer alignment, in great analogy with the (22×√3) Au(111) reconstruction.

Published
2021

9. Structure of Germanene/Al(111): A Two-Layer Surface Alloy

Author

Zhang, K., primary, Sciacca, D., additional, Hanf, M.-C., additional, Bernard, R., additional, Borensztein, Y., additional, Resta, A., additional, Garreau, Y., additional, Vlad, A., additional, Coati, A., additional, Lefebvre, I., additional, Derivaz, M., additional, Pirri, C., additional, Sonnet, P., additional, Stephan, R., additional, and Prévot, G., additional

Published
2021
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15. Strain and composition of ultrasmall Ge quantum dots studied by x-ray scattering and in situ surface x-ray absorption spectroscopy.

Author

Dujardin, R., Poydenot, V., Schülli, T. U., Renaud, G., Ulrich, O., Barski, A., Derivaz, M., Colonna, S., and Metzger, T.

Subjects
QUANTUM dots, GERMANIUM, THIN films, SILICON oxide, X-ray scattering, GRAZING incidence, ABSORPTION spectra
Abstract

Investigations of the structural properties of ultrasmall Ge dots, grown through a thin silicon oxide layer on Si(001), have been performed by combining (i) grazing incidence x-ray diffraction, (ii) grazing incidence small angle x-ray scattering (GISAXS), and (iii) surface extended x-ray absorption fine structure (SEXAFS). Grazing incidence x-ray diffraction observations show that the dots are highly strained to the Si(001) substrate. The dot shape and composition, as determined by GISAXS experiments and in situ SEXAFS, strongly depend on the thickness and the composition of the silicon oxide layer covering the surface of the silicon substrate. Ge dots grown through 1.2 nm thick SiO2 are round shaped with a Ge content of about 60% whereas dots grown through 0.3 nm thick SiOx are facetted and composed of almost pure Ge. [ABSTRACT FROM AUTHOR]

Published
2006
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17. Y2O3 MIM capacitors

Author

Vallée, Corentin, Durand, C., Dubourdieu, C., Blonkowski, S., Kahn, Myrtil L., Derivaz, M., Jalabert, D., Holiger, P., Bonvalot, M., and Clot, Marielle

Published
2005

18. MIM capacitors based on Yttrium oxide – Lanthanum aluminate stacks

Author

Kahn, Myrtil L., Vallée, Corentin, Dubourdieu, C., Durand, C., Blonkowski, S., Edon, V., Hugon, M.C., Agius, B., Voldoire, Olivier, Derivaz, M., Bonvalot, M., Baron, T., Clot, Marielle, Laboratoire des technologies de la microélectronique (LTM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), STMicroelectronics [Crolles] (ST-CROLLES), and Université Joseph Fourier - Grenoble 1 (UJF)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Published
2005

20. Roles of oxygen plasma and solvent in the interface formation during the pulsed-liquid injection PE-MOCVD deposition of Y2O3 in MIM and MOS structures

Author

Vallée, Corentin, Durand, C., Derivaz, M., Kahn, Myrtil L., Bonvalot, M., Clot, Marielle, Laboratoire des technologies de la microélectronique (LTM), Université Joseph Fourier - Grenoble 1 (UJF)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Published
2004

27. Surface energy minimization struggle between Ge and Si on 4H-SiC(0001)-(3 $\times $3)

Author

Dentel, D., Aït-Mansour, K., Derivaz, M., Kubler, L., Diani, M., Bolmont, D., Bischoff, J. L., Dentel, D., Aït-Mansour, K., Derivaz, M., Kubler, L., Diani, M., Bolmont, D., and Bischoff, J. L.

Abstract

The Ge growth behaviour on the 3$\times $3 Si-rich surface termination of 4H-SiC(0001) has been investigated in this study. After the deposit of one Ge monolayer at room temperature by molecular beam epitaxy, the film is submitted to isochronal annealing cycles up to 1000°C. A phase separation between Si and Ge is observed during the annealing process accompanied by successive 2D$/$3D and unusual 3D$/$2D transitions for both elements. Si and Ge struggle for wetting the bare surface in order to minimize its surface energy. This behaviour seems also to be related to the strain difference induced by the misfit of Si ($\sim $25%) and Ge (∼30%) with the 4H-SiC(0001) substrate.

Published
2006
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29. Ge quantum dots on a large band gap semiconductor: the first growth stages on 4H–SiC(0 0 0 1)

Author

Aït-Mansour, K., Dentel, D., Bischoff, J.L., Kubler, L., Diani, M., Barski, A., Derivaz, M., and Noé, P.

Subjects
*ELECTRON diffraction, *QUANTUM dots, *QUANTUM electronics, *MOLECULAR beam epitaxy, *SURFACE chemistry
Abstract

The Ge growth on SiC(0 0 0 1) follows a Stranski–Krastanov mode for Si-rich (3×3) and (√ of 3×√ of 3)R30° reconstructed surfaces. For Ge deposit in particular temperature conditions, a new (4×4) superstructure takes place and the reflection high energy electron diffraction (RHEED) specular spot intensity presents one oscillation proving a wetting layer formation. An island nucleation is then ascertained by the oscillation vanishing and by the appearance of a k⊥-modulated RHEED pattern. On the other hand, on a (6√ of 3×6√ of 3)R30° C-rich surface, a direct Ge island nucleation is observed from the first growth stage. Indeed, for 1 ML Ge, the RHEED diagram consists in spots and rings, and the atomic force microscopy analysis indicates a high density (∼8×1010 cm-2) of small islands (∅∼30 nm, h∼3 nm). The RHEED spot analysis shows a preferential epitaxial relationship with the substrate Ge(1 1 1)//SiC(0 0 0 1). The Ge–C bonding being energetically unfavourable, Ge tends to form islands immediately rather than wetting the graphite-terminated surface. The Ge growth mode on C-rich surface is thus of Volmer–Weber type. [Copyright &y& Elsevier]

Published
2004
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31. The Ground State of Epitaxial Germanene on Ag(111).

Author

Zhang K, Hanf MC, Bernard R, Borensztein Y, Cruguel H, Resta A, Garreau Y, Vlad A, Coati A, Sciacca D, Grandidier B, Derivaz M, Pirri C, Sonnet P, Stephan R, and Prévot G

Abstract

Two-dimensional (2D) honeycomb lattices beyond graphene, such as germanene, appear very promising due to their outstanding electronic properties, such as the quantum spin Hall effects. While there have been many claims of germanene monolayers up to now, no experimental evidence of a honeycomb structure has been provided up to now for these grown monolayers. Using scanning tunneling microscopy (STM), surface X-ray diffraction (SXRD), and density functional theory, we have elucidated the Ge-induced ( 109 × 109 ) R ± 24.5 ° reconstruction on Ag(111). We demonstrate that a powerful algorithm combining SXRD with STM allows us to solve a giant surface reconstruction with more than a hundred atoms per unit cell. Its extensive unit cell indeed consists of 98 2-fold or 3-fold coordinated Ge atoms, forming a periodic arrangement of pentagons, hexagons, and heptagons, with the inclusion of six dispersed Ag atoms. By analogy, we show that the ( 7 7 × 7 7 ) R ± 19.1 ° reconstruction obtained by segregation of Ge through an epitaxial Ag/Ge(111) film possesses a similar structure, i.e., Ge pentagons/hexagons/heptagons with a few Ag atoms. Such an organization is more stable than that of pure Ge monolayers and can be assigned to the ground state of epitaxial germanene.

Published
2023
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32. Account of the diversity of tunneling spectra at the germanene/Al(1 1 1) interface.

Author

Sciacca D, Peric N, Berthe M, Biadala L, Pirri C, Derivaz M, Massara N, Diener P, and Grandidier B

Abstract

Despite the wealth of tunneling spectroscopic studies performed on silicene and germanene, the observation of a well-defined Dirac cone in these materials remains elusive. Here, we study germanene grown on Al(1 1 1) at submonolayer coverages with low temperature scanning tunneling spectroscopy. We show that the tunnelling spectra of the Al(1 1 1) surface and the germanene nanosheets are identical. They exhibit a clear metallic behaviour at the beginning of the experiments, that highlights the strong electronic coupling between the adlayer and the substrate. Over the course of the experiments, the spectra deviate from this initial behaviour, although consecutive spectra measured on the Al(1 1 1) surface and germanene nanosheets are still similar. This spectral diversity is explained by modifications of the tip apex, that arise from the erratic manipulation of the germanium adlayer. The origin of the characteristic features such as a wide band gap, coherence-like peaks or zero-bias anomalies are tentatively discussed in light of the physical properties of Ge and AlGe alloy clusters, that are likely to adsorb at the tip apex.

Published
2020
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33. Tip-Induced Switch of Germanene Atomic Structure.

Author

Stephan R, Derivaz M, Hanf MC, Dentel D, Massara N, Mehdaoui A, Sonnet P, and Pirri C

Abstract

A new germanene crystallographic structure is investigated by scanning tunnelling microscopy and density functional theory calculations. We found that germanene can crystallize in two stable but different structures when grown on Al(111) at the same temperature. These structures are evidenced in scanning tunnelling images by a honeycomb contrast and by a hexagonal contrast. These contrasts are relevant of a Ge network with one (hexagonal) or two (honeycomb) Ge atoms per unit cell shifted upward with respect to the other Ge atoms. These structures appear alternatively and can be turned on and off by a tip-induced process.

Published
2017
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34. Continuous germanene layer on Al(111).

Author

Derivaz M, Dentel D, Stephan R, Hanf MC, Mehdaoui A, Sonnet P, and Pirri C

Abstract

Germanene, a 2D honeycomb structure similar to silicene, has been fabricated on Al(111). The 2D germanene layer covers uniformly the substrate with a large coherence over the Al(111) surface atomic plane. It is characterized by a (3 × 3) superstructure with respect to the substrate lattice, shown by low energy electron diffraction and scanning tunnelling microscopy. First-principles calculations indicate that the Ge atoms accommodate in a very regular atomic configuration with a buckled conformation.

Published
2015
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