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Dive into the research topics where Vincent Consonni is active.

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Featured researches published by Vincent Consonni.


Applied Physics Letters | 2009

Effects of nanowire coalescence on their structural and optical properties on a local scale

Vincent Consonni; M. Knelangen; Uwe Jahn; Achim Trampert; Lutz Geelhaar; H. Riechert

The effects of GaN nanowire coalescence have been investigated on a local scale by combining high-resolution transmission electron microscopy imaging with spatially resolved cathodoluminescence measurements. Coalescence induces the formation of a network of boundary dislocations, above which I1-type basal-plane stacking faults are nucleated. The former contributes to the reduction in the crystalline quality at the bottom of coalesced nanowires while the latter leads to intense excitonic radiative transitions at 3.42 eV in their center. Despite coalescence, the top of coalesced nanowires presents a very high crystalline quality, resulting in strong radiative recombinations of donor bound excitons at 3.47 eV.


Applied Physics Letters | 2011

Synthesis and physical properties of ZnO/CdTe core shell nanowires grown by low-cost deposition methods

Vincent Consonni; G. Rey; J. Bonaimé; N. Karst; Béatrice Doisneau; H. Roussel; S. Renet; Daniel Bellet

Vertically aligned ZnO/CdTe core/shell nanowire arrays have been grown by low-cost deposition techniques. ZnO nanowires have a wurtzite structure and are c-axis oriented. The CdTe shell completely covers ZnO nanowires and consists of nanograins, which are slightly oriented along the ⟨111⟩ direction owing to a grain growth process driven by surface energy minimization. Their nucleation follows the Volmer–Weber growth mechanism: in particular, island coalescence results in the generation of high tensile stress, which significantly reduces the CdTe optical band gap. Furthermore, both ZnO and CdTe exhibit excitonic emission bands around 3.36 eV and 1.56 eV, respectively.


ACS Nano | 2014

Selective Area Growth of Well-Ordered ZnO Nanowire Arrays with Controllable Polarity

Vincent Consonni; Eirini Sarigiannidou; Estelle Appert; Amandine Bocheux; Sophie Guillemin; Fabrice Donatini; Ivan-Christophe Robin; J. Kioseoglou; Florence Robaut

Controlling the polarity of ZnO nanowires in addition to the uniformity of their structural morphology in terms of position, vertical alignment, length, diameter, and period is still a technological and fundamental challenge for real-world device integration. In order to tackle this issue, we specifically combine the selective area growth on prepatterned polar c-plane ZnO single crystals using electron-beam lithography, with the chemical bath deposition. The formation of ZnO nanowires with a highly controlled structural morphology and a high optical quality is demonstrated over large surface areas on both polar c-plane ZnO single crystals. Importantly, the polarity of ZnO nanowires can be switched from O- to Zn-polar, depending on the polarity of prepatterned ZnO single crystals. This indicates that no fundamental limitations prevent ZnO nanowires from being O- or Zn-polar. In contrast to their catalyst-free growth by vapor-phase deposition techniques, the possibility to control the polarity of ZnO nanowires grown in solution is remarkable, further showing the strong interest in the chemical bath deposition and hydrothermal techniques. The single O- and Zn-polar ZnO nanowires additionally exhibit distinctive cathodoluminescence spectra. To a broader extent, these findings open the way to the ultimate fabrication of well-organized heterostructures made from ZnO nanowires, which can act as building blocks in a large number of electronic, optoelectronic, and photovoltaic devices.


Journal of Applied Physics | 2012

Thickness effects on the texture development of fluorine-doped SnO2 thin films: The role of surface and strain energy

Vincent Consonni; G. Rey; H. Roussel; Daniel Bellet

Polycrystalline fluorine-doped SnO2 thin films have been grown by ultrasonic spray pyrolysis with a thickness varying in the range of 40 to 600 nm. A texture transition from ⟨110⟩ to ⟨100⟩ and ⟨301⟩ crystallographic orientations has experimentally been shown by x-ray diffraction measurements as film thickness is increased, showing that a process of abnormal grain growth has occurred. The texture effects are considered within a thermodynamic approach, in which the minimization of total free energy constitutes the driving force for grain growth. For very small film thickness, it is found that the ⟨110⟩ preferred orientation is due to surface energy minimization, as the (110) planes have the lowest surface energy in the rutile structure. In contrast, as film thickness is increased, the ⟨100⟩ and ⟨301⟩ crystallographic orientations are progressively predominant, owing to elastic strain energy minimization in which the anisotropic character is considered in the elastic biaxial modulus. A texture map is eventua...


Applied Physics Letters | 2012

Scaling growth kinetics of self-induced GaN nanowires

V. G. Dubrovskii; Vincent Consonni; Lutz Geelhaar; Achim Trampert; H. Riechert

We present a kinetic model showing why self-induced GaN nanowires synthesized by molecular beam epitaxy obey the scaling growth laws. Our model explains the scaling behavior from kinetic considerations of the step flow radial growth and the shadow effect. The nanowire length L and radius R scale with time as [1+C(t-t0)]α/(α+1) and [1+C(t-t0)]1/(α+1), respectively. Consequently, the length scales with the radius as L∝Rα. The power index α equals 2.46 in our conditions. This scaling behavior is paramount for understanding the self-induced growth of nanowires in general as well as for tuning their morphology to the desired properties.


ACS Applied Materials & Interfaces | 2015

Physical Properties of Annealed ZnO Nanowire/CuSCN Heterojunctions for Self-Powered UV Photodetectors

Jérôme Garnier; Romain Parize; Estelle Appert; O. Chaix-Pluchery; Anne Kaminski-Cachopo; Vincent Consonni

The low-cost fabrication of ZnO nanowire/CuSCN heterojunctions is demonstrated by combining chemical bath deposition with impregnation techniques. The ZnO nanowire arrays are completely filled by the CuSCN layer from their bottoms to their tops. The CuSCN layer is formed of columnar grains that are strongly oriented along the [003] direction owing to the polymeric form of the β-rhombohedral crystalline phase. Importantly, an annealing step is found essential in a fairly narrow range of low temperatures, not only for outgassing the solvent from the CuSCN layer, but also for reducing the density of interfacial defects. The resulting electrical properties of annealed ZnO nanowire/CuSCN heterojunctions are strongly improved: a maximum rectification ratio of 2644 at ±2 V is achieved following annealing at 150 °C under air atmosphere, which is related to a strong decrease in the reverse current density. Interestingly, the corresponding self-powered UV photodetectors exhibit a responsivity of 0.02 A/W at zero bias and at 370 nm with a UV-to-visible (370-500 nm) rejection ratio of 100 under an irradiance of 100 mW/cm(2). The UV selectivity at 370 nm can also be readily modulated by tuning the length of ZnO nanowires. Eventually, a significant photovoltaic effect is revealed for this type of heterojunctions, leading to an open circuit voltage of 37 mV and a short circuit current density of 51 μA/cm(2), which may be useful for the self-powering of the complete device. These findings show the underlying physical mechanisms at work in ZnO nanowire/CuSCN heterojunctions and reveal their high potential as self-powered UV photodetectors.


Applied Physics Letters | 2011

Physical origin of the incubation time of self-induced GaN nanowires

Vincent Consonni; Achim Trampert; L. Geelhaar; H. Riechert

The nucleation process of self-induced GaN nanowires grown by molecular beam epitaxy has been investigated by reflection high-energy electron diffraction measurements. It is found that stable nuclei in the form of spherical cap-shaped islands develop only after an incubation time that is strongly dependent upon the growth conditions. Its evolution with the growth temperature and gallium rate has been described within standard island nucleation theory, revealing a nucleation energy of 4.9 ± 0.1 eV and a very small nucleus critical size. The consideration of the incubation time is critical for the control of the nanowire morphology.


Applied Physics Letters | 2011

Nucleation and coalescence effects on the density of self-induced GaN nanowires grown by molecular beam epitaxy

Vincent Consonni; M. Knelangen; Achim Trampert; L. Geelhaar; H. Riechert

The evolution of the density of self-induced GaN nanowires as a function of the growth time, gallium rate, and growth temperature has been investigated by scanning and transmission electron microscopy. Nucleation and coalescence effects have been disentangled and quantified by distinguishing between single nanowires and nanowire clusters. Owing to the very specific nanowire nucleation mechanism involving a shape transition from spherical-cap-shaped islands, the nanowire density does not follow the standard island nucleation theory. Furthermore, the detrimental nanowire coalescence process can be significantly reduced by raising the growth temperature.


Journal of Applied Physics | 2006

Spectroscopic analysis of defects in chlorine doped polycrystalline CdTe

Vincent Consonni; G. Feuillet; S. Renet

The effects of Cl doping of thick polycrystalline CdTe layers grown by close space sublimation on their crystalline structure and the compensation and passivation processes have been investigated. From an extensive low temperature photoluminescence study, it is shown that, in polycrystalline CdTe:Cl, the main compensation processes are similar to those occurring in monocrystalline CdTe:Cl. However, specific compensation processes are also evidenced in polycrystalline CdTe: Defect complexes can be formed between Cl atoms and impurities in the vicinity of extended defects such as dislocations, twin boundaries, and grain boundaries. Furthermore, using low temperature cathodoluminescence imaging, chlorine induced passivation processes are proposed for defects such as double positioning twin boundaries within the grains. On the structural side, a bimodal distribution of the grain size is found: While small grains (5μm in diameter) are predominant at low Cl doping (around 2×1017at.cm−3), larger grains (40μm in ...


Nanotechnology | 2010

In situ analysis of strain relaxation during catalyst-free nucleation and growth of GaN nanowires.

M. Knelangen; Vincent Consonni; Achim Trampert; H. Riechert

Strain relaxation mechanisms occurring during self-induced growth of nitride nanowires are investigated by in situ reflection high-energy electron diffraction and ex situ high-resolution transmission electron microscopy. Epitaxial GaN nanowires nucleate on an AlN buffer layer under highly nitrogen-rich conditions via the initial formation of coherently strained three-dimensional islands according to the Volmer-Weber growth mechanism. The epitaxial strain relief in these islands occurs by two different processes. Initially, strain is elastically relieved via several shape transitions. Subsequently, plastic relaxation takes place through the formation of a misfit dislocation at the GaN/AlN interface. At the same time, a final shape transition to fully relaxed nanowires occurs.

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Estelle Appert

Centre national de la recherche scientifique

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Daniel Bellet

Centre national de la recherche scientifique

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H. Roussel

Centre national de la recherche scientifique

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Laetitia Rapenne

Centre national de la recherche scientifique

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G. Rey

Centre national de la recherche scientifique

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O. Chaix-Pluchery

Centre national de la recherche scientifique

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Romain Parize

Centre national de la recherche scientifique

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Thomas Cossuet

Centre national de la recherche scientifique

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