All opportunities

Offers : 29

3D occupancy grid analysis with a deep learning approach

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Start date : 1 February 2018

offer n° PsD-DRT-18-0042

The context of this subject is the development of autonomous vehicles / drones / robots.

The vehicle environment is represented by a 3D occupancy grid, in which each cell contains the probability of presence of an object. This grid is refreshed over time, thanks to sensor data (Lidar, Radar, Camera).

Higher-level algorithms, like path planning or collision avoidance, think in terms of objects described by their path, speed, and nature. It is thus mandatory to get these objects from individual grid cells, with clustering, classification, and tracking.

Many previous publications on this topic comes from the context of vision processing, many of them using deep learning. They show a big computational complexity, and do not benefit from occupancy grids specific characteristics (lack of textures, a priori knowledge of areas of interest…). We want to explore new techniques, tailored to occupation grids, and more compatible with embedded and low cost implementation.

The objective of the subject is to determine, from a series of 3D occupation grids, the number and the nature of the different objects, their position and velocity vector, exploiting the recent advances of deep learning on unstrucured 3D data.

  • Keywords : Engineering science, Computer science and software, DACLE, Leti
  • Laboratory : DACLE / Leti
  • CEA code : PsD-DRT-18-0042
  • Contact :

Innovative GaN-on-Si power diode architectures for improved high current performance

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Start date : 1 March 2018

offer n° PsD-DRT-18-0027

Lateral GaN diodes, based upon a HEMT-type architecture (similar to GaN HEMT transistors) have been developed during several years by industrial (Transphorm, Panasonic…) and research (LETI, IMEC…) institutes. LETI has namely processed 650V lateral diodes using a 200mm GaN on Si epitaxy process with state of the art performance. Such performance is at the level of SiC diodes regarding low forward on-resistance and reduced reverse leakage current or high breakdown voltages. However, as the forward conduction is lateral and takes place within a two dimensionnal electron gas, such devices withstand very limited levels of current surges in comparison to SiC vertical diodes (10 times the nominal diode current during 10µs to 10ms).

Based upon existing componants and preliminary studies, LETI wishes to developp an innovative GaN-on-Si power diode architecture, allowing to achieve the same performance as those displayed by SiC diodes (namely JBS diodes: Junction Barrier Schottky Diodes), by using the possibilities offered by current GaN-on-Si technologies and those being currently developed.

  • Keywords : Engineering science, Electronics and microelectronics - Optoelectronics, Solid state physics, surfaces and interfaces, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-18-0027
  • Contact :

Development of lead free piezoelectric actuator

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Start date : 1 February 2018

offer n° PsD-DRT-18-0033

At CEA-Tech, the LETI Institute creates innovation and transfers it to industry. The micro-actuator component laboratory (LCMA) is working on the integration of piezoelectric materials into microsystems that allow electromechanical transduction. Lead zirconate titanate (PZT) is today the most powerful piezoelectric material for micro-actuator applications. However, the introduction in the near future of a new standard regarding the lead amount allowed in chips (European RoHS directive) leads us to evaluate alternative lead-free materials to PZT for piezoelectric actuator applications. The development of lead-free materials has thus become a major focus of piezoelectric research. This research led to revisit and modify some classical piezoelectric such as KNbO3 and BaTiO3. In particular, the KNaxNb1-xO3 (KNN) family has been identified as promising. The objective of the postdoc is therefore to evaluate some lead-free piezoelectric materials and to compare their properties with that of the reference material, PZT. Suitable test vehicles will be fabricated in LETI’s clean rooms for electrical and piezoelectric characterizations by mean of dedicated tools already available at lab. For this work the candidate will lean on a solid experience developed at LETI for more than 20 years on piezoelectric thin films.

  • Keywords : Engineering science, Materials and applications, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-18-0033
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Ge-on-Insulator (GeOI) substrates for photonics

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Start date : 1 February 2018

offer n° PsD-DRT-18-0045

The induction of tensile strain in intrinsic and doped Germanium (Ge) is one approach currently explored to transform the Ge indirect bandgap into a direct one. To take full advantage of Ge, we study the Ge CMOS photonics platform with Ge-on-Insulator (GeOI) structure, which enables strong 2D optical confinement in the Ge photonic-wire devices. One recent study in our lab showed the interest of a method of incorporation of mechanical stress into Ge, one of the essential ingredients of the laser. In particular, the method could be applied to the massive Ge, making compatible gap direct and crystalline quality.

Post-doc objectives : Development of GeOI substrates from massive Ge donors with tensile strain inside the Ge film. These developments will be realized from the existing Smart Cut / thinning processes, combined with technological steps to overcome their current limits (SAB bonding). The substrates obtained will be characterized to determine their state of deformation as well as their damage (Raman / XRD) and final GeOI substrates will be provided to the application laboratories for the production of photonic components.

  • Keywords : Engineering science, Electronics and microelectronics - Optoelectronics, Materials and applications, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-18-0045
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Nano-silicon/graphene composites for high energy density lithium-ion batteries

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Start date : 1 May 2018

offer n° PsD-DRF-18-0052

This postdoctoral fellowship is part of a Graphene Flagship H2020 european project on the energy storage applications of graphene. In lithium-ion batteries, graphene associated to nanostructured silicon in a proper composite helps increase the energy capacity. Indeed graphene wraps silicon, reducing its reactivity with electrolyte and the formation of the SEI passivation layer. It also maintains a high electrical conductivity within the electrode.

The study will compare two technologies: graphene-silicon nanoparticles and graphene-silicon nanowires. The former composite, already explored in the above mentioned project, will be optimized in the present study. The latter is a new kind of composite, using a large scale silicon nanowire synthesis process recently patented in the lab. The postdoc will work within two laboratories: a technological research lab (LITEN) with expertise in batteries for transportation, and a fundamental research lab (INAC) with expertise in nanomaterial synthesis.

The postdoc will synthesize silicon nanowires for his/her composites at INAC. Following LITEN know-how, she/he will be in charge of composite formulation, battery fabrication and electrochemical cycling. He/she will systematically compare the electrochemical behavior of the nanoparticle and nanowire based silicon-graphene composites. Comparison will extend to the mechanism of capacity fading and SEI formation, thanks to the characterization means available at CEA Grenoble and in the European consortium: X-ray diffraction, electronic microscopy, XPS, FTIR, NMR spectroscopies. She/he will report her/his work within the international consortium (Cambride UK, Genova Italy, Graz Austria) meetings.

PhD in materials science is requested. Experience in nanocharacterization, nanochemistry and/or electrochemistry is welcome.

  • Keywords : Engineering science, Materials and applications, Ultra-divided matter, Physical sciences for materials, INAC, SyMMES
  • Laboratory : INAC / SyMMES
  • CEA code : PsD-DRF-18-0052
  • Contact :
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