Nanoscale characterization using advanced TEM based techniques

( HR-TEM, HR-STEM, ED and Chemical analysis using EDX spectroscopy )

 LPICM is a member of the CIMEX( Centre Interdisciplinaire de Microscopie Electronique de l’X )  platform (https://portail.polytechnique.edu/cimex/) at Ecole Polytechnique regrouping mainly four laboratories having research topics in different domains from material and life science.

Potential application fields: Nanoscience, Condensed Matter Physics, Environmental Sciences, Energy Storage

Persons from the lab involved within the CIMEX platform:

Ileana Florea (lenuta-ileana.florea@polytechnique.edu)

Jean-Luc Maurice (jean-luc.maurice@polytchnique.edu)

Typical Studied materials:

• Carbon-based nanostructures: graphene, SWCNTs, or MWCNTs ;  
• Carbon-based hierarchical nanostructures used as electrodes for Li-Ion batteries;
• Semiconductor nanostructures: Si nanowires (NWs) & Ge NWs ;
• Metallic nanostructures: nickel silicide NWs;
• a-Si(amorphous Si), µc-Si (microcrystalline)  grown using the PECVD technique for photovoltaic applications;
• Si and Ge epitaxial thin films grown by low-temperature PECVD for photovoltaic applications.

Information  accessed through TEM characterization:

• nanostructure behaviors in different environments (gas, electric field, liquid, and electrochemistry)
• impact of  the synthesis parameters on the  morphological, structural, and chemical properties;
• atomic density at the interface of the deposited layers, particularly in the case of epitaxy;
• distribution of dopant atoms in the silicon thin films and nanowires;
• distribution of the catalyst atoms in the silicon nanowires and backward;
• atomic structure of the crystalline nuclei & of the grain boundaries in polymorphous silicon.

TEM based techniques

• Conventional TEM & STEM Imaging                         

            

 

• Chemical analyses using  spectroscopy techniques EDS et EELS

Chemical mapping  of CuS NPs

Cu/S/O/C  Relative map

Collaboration: M. Zamfir  & C.-S. Cojocaru

 

 

 

• HR-TEM at low voltage 60-80kV  

 

• Low dose HR-TEM using DDE K2 camera 

 

• In-situ dynamical studies within closed liquid cells or ETEMs 

TEM Accessories

Cameras: US1000 (2k×2k) with a recording speed of 4 fps (1k×1k); K2-IS DDE (4k×4k)  low dose (5-25 électrons.Å^-2s^-1) with a recording speed of 400 fps( 2k×2k) ; 800 fps(2k × 1k) and 1600 fps (2k × 0.5k ).

Specimen Stages: Two standard sample holders, one single tilt and one double tilt; Two heating sample holders (Fusion-Protochips ) specially design allowing reaching temperature range (25-1200°C); One liquid electrochemistry sample holder  (Poseidon 510-Protochips );

QMS 220 PrismaPlus de Pfeiffer Residual Gas Analyzer (RGA) allowing detection of reactants and products with a range of 1–100amu: