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A1 : DIAMOND & CARBON-BASED NANO-STRUCTURES
Article mis en ligne le 11 décembre 2017
dernière modification le 9 avril 2018
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Axe A : ELECTRONIC STRUCTURE-BASED FUNCTIONAL MATERIALS

A1 : Diamond and carbon based nano-structures for electronics and photonics

 

The " diamond and carbon-based nano-structures " sub-axis gather researchers who elaborate diamond -material with a high added value- at different scale (macro, micro or nanocrystalline) together with scientists who finely analyze carbon nano-structures (CNTs, graphene,..) or who study OLEDs. The electronic properties of carbon structures are studied in detail. Applications concern photonic devices, electronics including power electronics and molecular electronics, detectors, etc. The rationale for the carbon-based nano-structures and diamond is that they can be elaborated with the adapted purity and structusre. Other challenges are to be able to produce them in large scale and to make them amenable to a vast variety of chemical, electrochemical and physical treatments prior to their use as components in high-tech devices.

 
 

Lspm, in collaboration with ITODYS, LPL, MPQ and the Ile de France diamond-network, will focus on overcoming the scientific and technological bottelnecks that are still preventing diamond from playing a central role in the field of electronics (especially power-electronics), in opto-electronics and photonics. These efforts will include :

  • inhibiting dislocation propagation in bulk diamond using new methods involving etching treatments or thin film deposition (ELOG in particular)
  • fabricating diamond active/passive multi-layers (p, p+, n, intrinsic) (collaboration with GEMaC for n-doped layers)
  • depositing thin or ultra-thin films functionalised or nanostructured for sensor applications (DNA sensing for example)
  • fabricating color centres networks for quantum cryptography (in collaboration with ENS Cachan-Thales, and in the future MPQ) or photonic structures for OLED and organic lasers (collaboration between LPL and LSPM)
  • developing more and more efficient plasma reactors to contribute to the development of a real diamond industrial sector in France. Besides crystal growth, the project will include the development of new processes required to obtain either low dislocation structures or devices that can match the specifications. The teams, involved in diamond growth, diamond doping, its characterisation, their facilities in terms of reactors, diamond processing, modelling and growth. New collaborations will be developped between the Labex partners for plasma diagnostics (QCL spectroscopy, LSPM/MPQ) and for diamond functionalization (LSPM/ITODYS), and historical collaborations with complementary teams in the Paris region (GEMaC, ENS Cachan, CEA), in France (LAAS, IN), and international (Warwick in particular, GIA, ...) will be pursued or even reinforced. Organic / inorganic nanostructures : Oleds and organic lasers The LPL group in collaboration with LSPM will be concerned on controlling OLED color and achieving high Q microcavity. It will play on the thickness and the position of the well inside the structure, and it will study the residual absorption of the transparent and conductive electrodes (usually Indium Tin Oxide) used with the OLED heterostructure. Microcavities incorporating very transparent and conductive electrodes with reduced absorption will be developed to push the limits toward higher Q microcavities. New transparent and conductive electrodes obtained by Atomic Layer Deposition will be realized. Another limiting factor for high Q microcavities is the low refractive index of organic materials (typically n=1.7) limiting the reflectivities at the air interfaces at only few percent. Therefore OLEDs embedded in microcavities made with higher refractive index materials may exhibit better quality factors. Beyond oxyde nano-balls, one other possible candidate is diamond. With a good transparency and refractive index n=2.45, the nanostructured diamond can exhibit photonic band gap properties and thus photonic crystal microcavities with high Q factors can be fabricated. On top of the high Q photonic crystal defect cavities, diamond can be p-doped which makes it a potential candidate for OLED anode thanks to its good transparency and controllable conductivity. These microcavities will be made at LSPM.

Carbon nanostructures

CNTs. Based on the deep understanding of the local spectroscopy of carbon nanotubes MPQ Lab will study the functionalization and doping of CNTs by STM in order to reveal their influence on the electronic structure of CNTs. In collaboration with LSPM that is able to produce pure or functionalized CNTs or BN and BCN nanotubes, the local electronic structure of these tubes and the effect of their functionalization down to the atomic scale will be studied. Using local spectroscopy, a large range of carbon based model systems for molecular electronics can be investigated. Diamond crystals will be studied by STM as well thanks to a new collaboration between MPQ and LSPM. These local STM studies will be completed by transport measurements.

is a simple test molecule before more complex molecules will be used after synthesis at ITODYS. C60 molecules will be deposited in situ at 4 K inside a nanogap after the electromigration process in order to investigate how the experimental signatures of quantum transport are modified in presence of a molecule and how the molecular levels interact with the electronic and spin degrees of freedom in the electrodes. Graphene. The main topic of this research will be the observation of spin and charge collective excitations in graphene in the quantum Hall effect regime and the study of the resonant coupling between vibrational and electronic degrees of freedom of the graphene layer using an optical tool inelastic light scattering, also known as Raman scattering. The experimental set-up developed at MPQ (SQUAP team) will be based on a split-coil magnet specially designed for optical studies and capable of reaching magnetic fields of 10T and temperatures as low as 1.5K. If successful it may pave the way to future Raman studies of electronic properties of other promising two-dimensional crystals like chalcogenides.








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