CNRS/C2N : Internship Training, PhDs and Post-docs Proposals (LPN) 
Centre for Nanosciences and Nanotechnology - Marcoussis Campus
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Internship Training, PhDs and Post-docs Proposals
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Internship Training Proposals

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Here is a list of Internship Training, PhDs and Post-Docs proposals. You can also refer to current Internship Training.

Puce Post-docs


  • Optomechanically-driven microwave oscillator

  • Contact : R. Braive
    Group : NanoPhotonIQ (NanoPhotonIQ)
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    Recent advances in nanophotonics have enabled co-design of mechanical and optical resonances in the same device, opening the way to optomechanics experiments at nanoscale. A notable contribution that has come out of this area, is the manifestation of parametric instability, resulting in mechanical amplification and thereby oscillation of the mechanical mode driven purely optically. This ability to achieve self-sustained oscillation with no need for feedback electronics makes optomechanical oscillators compelling for on-chip applications such as microwave clocks, in which directed light energy from a laser is available to fuel the oscillation. In this project, the photonic clock architecture will rely on an integrated high-quality optomechanical nanoresonator, in order to achieve very stable oscillation in the GHz range, where the lack of good quality and miniaturized sources is a severe issue. Thanks to the strong reduction of the oscillator dimensions down to nanoscale, the resonator will sustain mechanical modes strongly coupled to light up to 3-5 GHz, directly at the operating frequency of interest for optoelectronic microwave oscillators and metrology applications. One main issue is the stability of the oscillator's output, as gauged over short time spans by its phase noise. Stabilization will be achieved by implementing on-chip optoelectronic loops, exploiting either an optical or acoustic control of mechanical motion along different schemes including locking on a reference frequency or self-injection locking. This project will be carried out in strong collaboration with Thales-RT for the specifications of the devices and their phase noise measurements .
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Puce PhDs


  • Growth of advanced functional heterostructures in III-V nanowires

  • Contact : F. Glas , J.-C. Harmand
    Group : Elaboration and Physics of Epitaxial Structures (ELPHYSE)
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    Context
    Semiconductor nanowires, with diameters of a few tens of nanometers and lengths up to several microns, are nowadays commonly fabricated from a large range of semiconductor materials. The remarkable physical properties of these objects open large prospects of original applications, some of which have already been demonstrated. However, their full potential will only be achieved if their physical properties can be precisely tailored. In addition to controlling the geometry, crystal structure and doping of the nanowires, two requirements are essential for most applications: (1) to obtain regular arrays of identical nanowires; (2) to confer novel functionalities to each nanowire by modulating locally its properties. The ultimate aim of the project is to combine these two objectives in the fabrication of arrays of nanowires including advanced functional heterostructures.

    PhD position
    Work will be carried out in the framework of the Marie Skłodowska-Curie European ITN project INDEED, that gathers 11 academic labs, 2 industrial partners plus associated partners. The PhD student at C2N (Marcoussis, then Palaiseau) will perform research on the growth by molecular beam epitaxy (MBE) of nanowires of III-V semiconductors. An important aspect of the project is to maintain an intimate coupling between experimental investigations and modeling of the nucleation and growth mechanisms, which is a strength of the C2N team. I, he/she will explore the growth of two kinds of heterostructures. The first one involves a high aspect ratio quantum size insertions of a material different from the rest of the nanowire. The second one consists in a nanowire where a spatial modulation of the electronic properties will be achieved by varying the diameter of the structure rather than composition. He/she will aim at fabricating arrays of such structures on a patterned substrate with a high yield of vertical and identical nanowires. The candidate is expected to develop and perform advanced modeling of the growth of these structures and to investigate experimentally their fabrication.

    References
    F. Glas, J. C. Harmand and G. Patriarche, Phys. Rev. Lett. 99, 146101 (2007)
    F. Glas, M. R. Ramdani, G. Patriarche, J.-C. Harmand, Phys. Rev. B 88, 195304 (2013)
    G. Priante, F. Glas, G. Patriarche, K. Pantzas, F. Oehler, J.-C. Harmand, Nano Lett. 16, 1917-1924 (2016)

    Contacts
    frank.glas@c2n.upsaclay.fr
    jean-christophe.harmand@c2n.upsaclay.fr

  • Integrated nano-optomechanics

  • Contact : R. Braive
    Group : NanoPhotonIQ (NanoPhotonIQ)


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  • Nano-optomechanics for time-frequency metrology and microwave photonics : Towards an optomechanically-driven microwave oscillator

  • Contact : R. Braive
    Group : NanoPhotonIQ (NanoPhotonIQ)
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    L'optomecanique

  • Coupled Micropillar lasers for neuromimetic information processing

  • Contact : S. Barbay
    Group : NanoPhotonIQ (NanoPhotonIQ)


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    We have recently shown that a micropillar laser with saturable absorber can behave analogously to a biological neuron but with characteristic timescales one million times faster. It can generate optical action potentials and possess a relative and an absolute refractory period. By coupling several of these lasers it is possible to fabricate neural networks with new functional properties. These systems, while being very recent and still in the course of developments, represent an alternative path for optical processing of information with respect to traditional architectures. The goal of the PhD project is to set up experiments in view of understanding the physics of such systems to contribute to the design and fabrication of the samples that take place in the LPN clean room facilities. In particular the candidate will explore the physics of coupled micropillar lasers, the propagation of nonlinear waves and the implementation of novel bio/neuro-inspired functionalities. More info

  • Highly conductive III-V/Si hybrid heterointerfaces for ultimate photonic integration schemes

  • Contact : A. Talneau
    Group : Optic of Semiconductor nanoStructures Group (GOSS)


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    Contexte :
    While the mechanical and optical integration of III-V semiconductors on Si have been repeatedly addressed in twenty years of silicon photonics, the possibility of electric and electronic integration of these hybrid engineered materials at the atomic scale has been left unexplored, despite the potentially immense gains in terms of thermal-budget improvement, chip power consumption, footprint and the integration of control electronics to boost data transfer rates. Adding this functionality to the actual devices design will allow exploiting the full potential of 3D integration.
    LPN has developed oxide-free bonding of III-V materials on Si [1], and has recently demonstrated electrical transport across such an interface [2]. LPN has the technology facility and characterization equipments for the elaboration of hybrid interfaces, and for the fabrication of photonic hybrid devices including such an interface. The group of Pr. Dollfus in IEF has the expertise for the simulation of electrical transport across the interface. IEF and LPN will merge in January 2016 to create the Centre de Nanosciences et de Nanotechnologies, C2N, on the Plateau de Saclay.
    Method :
    This PhD work proposes to elaborate III-V/Si heterointerfaces by the bonding technology, and to investigate, understand, and quantify electrical transport across these hybrid interfaces, for several III-V materials and several doping concentration. This transport behaviour will first be simulated, and then experimentally characterized on the fabricated interfaces. Then an hybrid photonic laser will be fabricated including an electrically injected interface by placing one electrode on the Si guiding layer. Such an electrical scheme is expected to greatly improve the thermal behaviour, still poor in the actual hybrid lasers.
    Objectives :
    The main objective of this PhD work is to demonstrate the operation of an hybrid III-V/Si laser emitting at 1.55µm, under electrical injection through the hybrid interface.
    For this goal, the PhD work will be involved in :
    • Elaboration by bonding technology and characterization of III-V/Si conductive hybrid interfaces;
    • Simulation and experimental characterization of the interface transport behaviour;
    • Design, fabrication and characterization of an hybrid laser operating under electrical injection through the interface.

    At the end of this PhD work, the candidate will have acquired knowledge and expertise in optoelectronics both in electronics and photonics, photonic hybrid devices design fabrication an characterization, and nanotechnology covering both the III-V semiconductor materials and their nanostructuration.

    [1] A. Talneau et al., Appl. Phys. Lett. 102, 212101 (2013)
    [2] K.Pantzas et al., IPRM (2014)
    Also
    K.Tanabe, S.Iwamoto and Y.Arakawa, IEICE Elec.Ex., 8, 596 (2011)
    K.Tanabe, K.Watanabe and Y.Arakawa, Scient.Rep. 2, 349 (2012)

    The financial support is the doctoral allocation from EDOM.
    Also on ADUM.fr

    Additional information : contact : Anne TALNEAU
    e-mail :
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Puce Internship Training

Master 2


  • Nanostructured optical waveguide array for hybrid isolator on silicon

  • Level : Master2
    Contact : A. Talneau , G. Patriarche
    Group : Optic of Semiconductor nanoStructures Group (GOSS)
                Elaboration and Physics of Epitaxial Structures (ELPHYSE)


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    Silicon will be the future of integrated photonics. Garnet should be associated to Si to provide integrated optical isolation. C2N has developed an oxide-free bonding technique [1] of both materials that enables preserving any structuration included in the silicon waveguide. Such a nanostructuration is a very versatile tool for designing tailored structures dedicated to advanced optical functions [2].
    The internship aims at studying specific design for optical isolators [3]. LUMERICAL commercial simulation tool will be used to fix the geometrical parameters of the waveguide array. C2N Marcoussis has large clean room facilities where devices will be fabricated, first on SOI to validate the design, and later on hybrid garnet/Si to demonstrate the isolation operation. Measurements will be performed on an end-fire set-up.
    This internship is undertaken in the framework of the ANR ISOLYIG project.
    The student may acquire knowledge in device simulation, clean-room nano-fabrication techniques and experimental optical characterization.

    [1] K.Pantzas et al., Appl. Phys. Lett.,105,141601 (2014)
    [2] A.Talneau et al., Opt. Lett., 40,5148 (2015)
    [3] R.El-Ganainy et al., Appl. Phys. Lett. 103,161105 (2013)

  • Synthesis of p-type TiO2 by sol-gel method and its Nano-structuration by Nanoimprint Lithography

  • Level : Master2
    Contact : A. Cattoni
    Group : Photonic devices (PHODEV)


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    Solar cells are mainly based on p-n junctions despite not strictly essential nor optimal. Ideally, photo-generated electron-hole in an intrinsic semiconductor material would be separated and collected through selective membranes such that electrons can only flow out to one side and holes to the other. The ideal electron membrane would be a wide band gap semiconductor with high electron conductivity and high electron affinity to collect the electrons and prevent hole injection. TiO2 is a good example and is actually used in dye-sensitized solar cells as efficient electron membrane. Corresponding p-type transparent conducting oxides, were surprisingly missing in thin film form for a long time until in 1997, Kawazoe et al. reported p-type conductivity in a highly transparent thin film of copper aluminum oxide (CuAlO2), but with a conductivity significantly lower than that observed for the best n-type conducting oxides. Interestingly, also TiO2 was observed to have p-type conductivity when synthesized under specific conditions. Moreover, TiO2 is largely used in diffractive nanophotonics devices having the highest refractive index among transparent materials in the visible. In this contest, we have developed a Nanoimprint process for the direct nano-structuration of TiO2 prepared by sol-gel method for light-trapping in solar cells or sensing applications. The goal of the stage is to identify the key parameters to synthesize p-type TiO2 by sol-gel method compatible with the Nanoimprint process. The focus will be on the role played by oxygen in the non-stoichiometric defect and carrier compensation of undoped TiO2 during sample preparation or annealing. The candidate will take care of the synthesis of the TiO2 sol-gel, its optical (Ellipsometry), electrical (Hall effect) and structural (SEM and EDX) characterization. Finally, she/he will apply the Nanoimprint process for the fabrication of nanostructured back-contact/mirror for ultra-thin solar cells. This project will be partially carried out at the "Centre de Nanosciences et de Nanotechnologies" (CNRS, Marcoussis) and at the "Laboratoire de Chimie de la Matière Condensée de Paris" (UPMC, Paris).

  • Ultrathin Nanostructured Solar Cells : towards record efficiencies

  • Level : Master2
    Contact : S. Collin , A. Cattoni
    Group : Photonic devices (PHODEV)


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    Reducing the absorber thickness is a major issue for most photovoltaic technologies because of material scarcity, material cost and/or process cost. Moreover, it results in an increase of the photogenerated charge density, which is also a key step towards high-efficiency solar cells based on advanced concepts like hot carrier solar cells. However, novel light-trapping schemes are required to compensate for the low single-pass absorption of very thin films. Nanophotonics and nanofabrication techniques provide new tools to go in this direction. In this context, we have developed a new light-trapping strategy based on multi-resonant absorption, and we are currently developing ultra-thin solar cells based on various materials including III-V semiconductors (GaAs, InP), crystalline silicon (c-Si) and CIGS. We have recently proposed novel light-trapping architectures based on nanostructured back mirrors. We have also developed original techniques for low-cost and large-area nanofabrication of solar cells applied to GaAs and c-Si solar cells. This work has resulted in the recent demonstration of state-of-the-art ultrathin solar cells with record short-circuit currents (GaAs, c-Si), confirming the relevance of this approach. The short-term objective of this work is to optimize the conception (both optically and electronically) and the fabrication process of ultrathin solar cells (thickness ~200 nm) in order to reach record conversion efficiencies (η→20%). The first task of this internship project will be to integrate improved architectures and novel methods in the fabrication process (high aspect-ratio nanostructures, point contacts, novel heterostructures, lift-off for reusable substrates, ALD passivation,…). The candidate will be involved in the fabrication of the solar cells (clean room facility). He will be in charge of the full characterization of the devices (home-made setups) through spectral and optoelectronic measurements (reflectivity, EQE, dark IV and IV under 1-sun illumination). The performances will be analyzed with the optical and electrical modeling tools available in our team. This project will be carried out at C2N, site de Marcoussis, in close collaboration with several partner labs of the “Fédération de Recherche Photovoltaïque d'Ile-de-France” and in the new “Institut photovoltaïque d’Ile-de-France” (IPVF). We plan to offer opportunities for PhD grants on novel concepts for high-efficiency, nanoscale solar cells.

  • Time-resolved cathodoluminescence: nanoscale characterization of photovoltaic materials

  • Level : Master2
    Contact : S. Collin
    Group : Photonic devices (PHODEV)


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    A new cathodoluminescence (CL) setup has been installed at C2N/Marcoussis at the end of 2015. Its basic principle is the following (see the figure): a material is excited with an electron beam in a scanning electron microscope (SEM), providing a spatial resolution of 10nm. Secondary electrons (SE), emitted photons (CL) and event electron-beam-induced current (EBIC) are collected and recorded simultaneously in order to form 2D maps. For each spatial position, CL spectra provide information on the luminescence efficiency, band structure and defects. In our tool, laser-controlled bunches of electrons can also be used for excitation instead of a continuous beam, resulting in time-resolved CL measurements (TRCL) that provide valuable information on carrier dynamics and lifetime. Our CL/TRCL setup has state-of-the-art specifications and is extremely versatile: wide spectral range 200nm-1600nm, wide range of temperatures (10K-400K), time-resolved measurements (temporal resolution 10ps). In addition, its very high collection efficiency on a wide field of view is perfectly adapted to CL and TRCL mapping of a wide variety of photovoltaic materials: defects and quantum structures (quantum wells, quantum dots,…) in bulk materials, polycrystalline semiconductors (CdTe, CIGS,…), nanomaterials (nanowires, nanopillars,…),... Passivation is becoming a key for high-efficiency photovoltaics and nanostructured solar cells. However, the development of novel passivation solutions is hindered by the lack of direct characterization techniques. The goal of this internship is to investigate the passivation efficiency of semiconductor surfaces with TRCL/CL/EBIC measurements, in the framework of internal and collaborative projects. TRCL/CL/EBIC mapping should bring fruitful insights to asset the efficiency of various passivation techniques. The candidate will be first trained on the CL/TRCL tool. Its first task will be to develop the methodology for the characterization of passivation layers using well-known GaAs reference samples. She/he will be involved in the preparation of samples in clean room. Next, she/he will apply this technique to the passivation of novel solar cell architectures (GaAs nanowire solar cells, nanotextured and ultrathin CIGS solar cells, localized ohmic contacts,…). In this context, she/he will work with several people in the team and he will be involved in internal and collaborative projects, in close collaboration with several partner labs of the new “Institut photovoltaïque d’Ile-de-France” (IPVF). We plan to offer opportunities for a PhD grant on CL/TRCL characterization of photovoltaic nanomaterials.

  • Coupled Micropillar lasers for neuromimetic information processing

  • Level : Master2
    Contact : S. Barbay
    Group : NanoPhotonIQ (NanoPhotonIQ)


    More
    We have recently shown that a micropillar laser with saturable absorber can behave analogously to a biological neuron but with characteristic timescales one million times faster. It can generate optical action potentials and possess a relative and an absolute refractory period. By coupling several of these lasers it is possible to fabricate neural networks with new functional properties. These systems, while being very recent and still in the course of developments, represent an alternative path for optical processing of information with respect to traditional architectures. The internship consists in participating to the experiments led in order to understand the physics of such systems and contributing to the fabrication of the samples that take place in the LPN clean room facilities. The internship can be followed by the start of a PhD program. More info
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