Thomas David
Aix-Marseille University
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Publication
Featured researches published by Thomas David.
Science Advances | 2017
Meher Naffouti; Rainer Backofen; Marco Salvalaglio; Thomas Bottein; Mario Lodari; Axel Voigt; Thomas David; Abdelmalek Benkouider; Ibtissem Fraj; L. Favre; A. Ronda; I. Berbezier; David Grosso; M. Abbarchi; Monica Bollani
Si-based nanoarchitectures are formed with unprecedented precision and reproducibility via templated dewetting of thin SOI. Dewetting is a ubiquitous phenomenon in nature; many different thin films of organic and inorganic substances (such as liquids, polymers, metals, and semiconductors) share this shape instability driven by surface tension and mass transport. Via templated solid-state dewetting, we frame complex nanoarchitectures of monocrystalline silicon on insulator with unprecedented precision and reproducibility over large scales. Phase-field simulations reveal the dominant role of surface diffusion as a driving force for dewetting and provide a predictive tool to further engineer this hybrid top-down/bottom-up self-assembly method. Our results demonstrate that patches of thin monocrystalline films of metals and semiconductors share the same dewetting dynamics. We also prove the potential of our method by fabricating nanotransfer molding of metal oxide xerogels on silicon and glass substrates. This method allows the novel possibility of transferring these Si-based patterns on different materials, which do not usually undergo dewetting, offering great potential also for microfluidic or sensing applications.
Small | 2016
Meher Naffouti; Thomas David; Abdelmalek Benkouider; L. Favre; Anne Delobbe; A. Ronda; I. Berbezier; M. Abbarchi
Thin film dewetting can be efficiently exploited for the implementation of functionalized surfaces over very large scales. Although the formation of sub-micrometer sized crystals via solid-state dewetting represents a viable method for the fabrication of quantum dots and optical meta-surfaces, there are several limitations related to the intrinsic features of dewetting in a crystalline medium. Disordered spatial organization, size, and shape fluctuations are relevant issues not properly addressed so far. This study reports on the deterministic nucleation and precise positioning of Si- and SiGe-based nanocrystals by templated solid-state dewetting of thin silicon films. The dewetting dynamics is guided by pattern size and shape taking full control over number, size, shape, and relative position of the particles (islands dimensions and relative distances are in the hundreds nm range and fluctuate ≈11% for the volumes and ≈5% for the positioning).
Nano Letters | 2017
Thomas David; Kailang Liu; A. Ronda; L. Favre; M. Abbarchi; Marc Gailhanou; Pascal Gentile; Denis Buttard; V. Calvo; Michele Amato; Jean-Noël Aqua; I. Berbezier
Selective oxidation of the silicon element of silicon germanium (SiGe) alloys during thermal oxidation is a very important and technologically relevant mechanism used to fabricate a variety of microelectronic devices. We develop here a simple integrative approach involving vapor-liquid-solid (VLS) growth followed by selective oxidation steps to the construction of core-shell nanowires and higher-level ordered systems with scalable configurations. We examine the selective oxidation/condensation process under nonequilibrium conditions that gives rise to spontaneous formation of core-shell structures by germanium condensation. We contrast this strategy that uses reaction-diffusion-segregation mechanisms to produce coherently strained structures with highly configurable geometry and abrupt interfaces with growth-based processes which lead to low strained systems with nonuniform composition, three-dimensional morphology, and broad core-shell interface. We specially focus on SiGe core-shell nanowires and demonstrate that they can have up to 70% Ge-rich shell and 2% homogeneous strain with core diameter as small as 14 nm. Key elements of the building process associated with this approach are identified with regard to existing theoretical models. Moreover, starting from results of ab initio calculations, we discuss the electronic structure of these novel nanostructures as well as their wide potential for advanced device applications.
Scientific Reports | 2018
Thomas David; Jean-Noël Aqua; Kailang Liu; L. Favre; A. Ronda; M. Abbarchi; Jean-Benoît Claude; I. Berbezier
Strain engineering is seen as a cost-effective way to improve the properties of electronic devices. However, this technique is limited by the development of the Asarro Tiller Grinfeld growth instability and nucleation of dislocations. Two strain engineering processes have been developed, fabrication of stretchable nanomembranes by deposition of SiGe on a sacrificial compliant substrate and use of lateral stressors to strain SiGe on Silicon On Insulator. Here, we investigate the influence of substrate softness and pre-strain on growth instability and nucleation of dislocations. We show that while a soft pseudo-substrate could significantly enhance the growth rate of the instability in specific conditions, no effet is seen for SiGe heteroepitaxy, because of the normalized thickness of the layers. Such results were obtained for substrates up to 10 times softer than bulk silicon. The theoretical predictions are supported by experimental results obtained first on moderately soft Silicon On Insulator and second on highly soft porous silicon. On the contrary, the use of a tensily pre-strained substrate is far more efficient to inhibit both the development of the instability and the nucleation of misfit dislocations. Such inhibitions are nicely observed during the heteroepitaxy of SiGe on pre-strained porous silicon.
Journal of Physical Chemistry C | 2015
Thomas David; Abdelmalek Benkouider; Jean-Noël Aqua; Martiane Cabié; L. Favre; Thomas Neisius; M. Abbarchi; Meher Naffouti; A. Ronda; Kailang Liu; I. Berbezier
Nanoscale | 2016
Meher Naffouti; Thomas David; Abdelmalek Benkouider; L. Favre; A. Ronda; I. Berbezier; Sébastien Bidault; Nicolas Bonod; M. Abbarchi
ACS Photonics | 2017
Thomas Wood; Meher Naffouti; Johann Berthelot; Thomas David; Jean-Benoît Claude; Léo Métayer; Anne Delobbe; L. Favre; A. Ronda; I. Berbezier; Nicolas Bonod; M. Abbarchi
Advanced Functional Materials | 2017
Thomas Bottein; T. J. Wood; Thomas David; Jean Benoît Claude; L. Favre; I. Berbezier; A. Ronda; M. Abbarchi; David Grosso
Nanotechnology | 2016
Meher Naffouti; Thomas David; Abdelmalek Benkouider; L. Favre; Martiane Cabié; A. Ronda; I. Berbezier; M. Abbarchi
Journal of Crystal Growth | 2013
Thomas David; Luc Roussel; Thomas Neisius; Martiane Cabié; Marc Gailhanou; Claude Alfonso