Géraldine Hallais

CNRS engineer (IEHC)

Géraldine Hallais is a CNRS engineer in the POEM platform of C2N in charge of development and characterization of semi-conductive nanostructures. She is the lead engineer for the UHV-CVD-CBE tool and the LASER EXCIMER doping or annealing tool of the C2N, in charge of day-to-day operation of these tools and their maintenance. She is also the C2N referent for XPS-AES (X-ray Photon-electron Spectrometry-Auger Electrons Spectrometry) surface analyses.  

Previously, she worked in 2 private sector companies. She was a component reliability engineer at ALCATEL CIT (2000-2005) in charge of developing a failure analysis method for laser pumps (InGaAs / GaAs) in the field of optoelectronics. She was then manager of the materials analysis laboratory in a start-up spin-off of CEA ALCHIMER (2005-2010) which developed and marketed nano-micrometric deposition and surface functionalization technologies in 2 fields of main applications: microelectronics (Through Silicon Via), Interconnect) and biomedical (coating of cardiovascular implants). 

She joined the CNRS in 2011, in the chemistry department of the Ecole Normale Supérieure (ENS). The only permanent member of the research federation « Sciences Chimiques de la Mesure et de l’Analyse de Paris Centre FR2702 », she was responsible for a clean room and an analysis room, in addition to her work as an engineer which consisted of to adapt and implement techniques of micro-nano fabrications and associated characterizations for microfluidic studies. 

Currently, she develops and optimizes growth processes for elaboration of nanometric hetero-structures based on semiconductor elements of the III-IV-V columns integrated on a silicon substrate for applications in photovoltaic, thermoelectricity and microelectronics according to 4 techniques: lateral epitaxy, selective epitaxy, 2D epitaxy, nanowires. Too, she develops and optimizes the doping and the epitaxy processes of Ge and Si by LASER fusion: GILD-PLIE (Gaz immersion Laser Doping - Pulsed Laser Induced Epitaxy). 

Her current research topics involve: 

- Integration of III-V materials (AlGaAs) lattice mismatched on silicon without stress defects emission by lateral epitaxy through nanoscale openings in a SiO2 layer of a few manometers (0.6 to 5nm). 

- Selective Epitaxial Growth (SEG) of localized (Si)Ge and Si layers on patterned silicon wafer or the whole wafer growth of large epi-layers SiGe with no segregation for the manufacture of pixel position sensitive detector with high micrometric resolution. 

- Heterostructured (axial or lateral) nanowires Ge, Si and III-V growth  

- The superconducting properties of heavily doped B Si by GILD 

- doping by GILD of the nanowires of Si and Ge 

- 2D epitaxy of Ge by PLIE on mesh disagreeing substrates 


Expertise fields: 

  • in material analysis  

XPS, AES, AFM (Atomic Force Microscopy), conductive AFM, Ellipsometry, SEM (Scanning Electronic Microscopy with EDX Energy Dispersive of X ray CL CathodoLuminescence and EBIC electron beam induced current analysis), FIB (focused ions Beam), CLS (Confocal Laser Scanning), TIRF (Total Internal Reflection Fluorescence Microscopy), TOF-SIMS (Time Of Flight Secondary Ions Mass Spectrometry), FTIR, XRD, HAADF-STEM  

  • in material growth 

GILD-PLIE (Gaz immersion Laser Doping - Pulsed Laser Induced Epitaxy) 

UHV-CVD-CBE (Ultra-High vaccum-chemical vapor deposition -chemical beam epitaxy) 


  • in process technology 

Electron lithography 

UV, Laser lithography  

Dry and wet etching 

PVD coating… 

She is the author and co-author of articles in peer-reviewed journals. A full list of the projects and articles she is involved in can be found on the webpages of the Seeds and EPLA teams of C2N. 

Involved in POEM Platform, SEEDs team, EPLA team 



For a full list and metrics, have a look to ResearchGate





Email address geraldine.hallais@c2n.upsaclay.fr

Office number

10 Bd Thomas Gobert
91120 Palaiseau  FRANCE

Phone number
+33 1 70 27 03 49


Research areas

  • Selective Epitaxy
  • III-V integration on Si

Current research projects