Dark-field electron holography for the mapping of strain in nanostructures: correcting artefacts and aberrations

Martin Hÿtch (1) , Florent Houdellier (2) , Florian Hüe (1) , Etienne Snoeck (1)

1 CEMES - Centre d'élaboration de matériaux et d'études structurales
2 CEMES-I3EM - Interférométrie, In situ et Instrumentation pour la Microscopie Electronique

We present details of the new electron holographic dark-field technique (HoloDark) for mapping strain in nanostructures. A diffracted beam emanating from an unstrained region of crystal is interfered (with the aid of an electrostatic biprism) with a diffracted beam from the strained region of interest. Geometric phase analysis (GPA) of the holographic fringes determines the relative deformation of the two crystalline lattices. Strain can be measured to high precision, with nanometre spatial resolution and for micron fields of view. Experiments are carried out on the SACTEM-Toulouse, a Tecnai F20 (FEI) equipped with imaging aberration corrector (CEOS), field-emission gun and rotatable biprism (FEI). We operate the microscope in free-lens control with the main objective lens switched off and using the corrector transfer lenses as a Lorentz lens. We will present measurements of strain in test nanostructures and show how artefacts from thickness variations can be removed. Finally, we show our first results using a recently developed aberration-corrected Lorentz mode (CEOS).

Domaines: Optique [physics.optics]; Physique des Hautes Energies - Expérience [hep-ex]; Physique Quantique [quant-ph]; Physique des accélérateurs [physics.acc-ph]; Electromagnétisme; Matériaux; Optique / photonique; Traitement du signal et de l'image [eess.SP]

Martin Hÿtch, Florent Houdellier, Florian Hüe, Etienne Snoeck. Dark-field electron holography for the mapping of strain in nanostructures: correcting artefacts and aberrations. Journal of Physics: Conference Series, 2010, 241, pp.012027. ⟨10.1088/1742-6596/241/1/012027⟩. ⟨hal-01742031⟩