Differential phase-contrast dark-field electron holography for strain mapping

Thibaud Denneulin (1) , Florent Houdellier (1) , Martin Hÿtch (1)

1 CEMES - Centre d'élaboration de matériaux et d'études structurales

Strain mapping is an active area of research in transmission electron microscopy. Here we introduce a dark-field electron holographic technique that shares several aspects in common with both off-axis and in-line holography. Two incident and convergent plane waves are produced in front of the specimen thanks to an electrostatic biprism in the condenser system of a transmission electron microscope. The interference of electron beams diffracted by the illuminated crystal is then recorded in a defocused plane. The differential phase recovered from the hologram is directly proportional to the strain in the sample. The strain can be quantified if the separation of the images due to the defocus is precisely determined. The present technique has the advantage that the derivative of the phase is measured directly which allows us to avoid numerical differentiation. The distribution of the noise in the reconstructed strain maps is isotropic and more homogeneous. This technique was used to investigate different samples: a Si/SiGe superlattice, transistors with SiGe source/drain and epitaxial PZT thin films. © 2015 Elsevier B.V.

Mots clés: Differentiation (calculus); Electron holography; Electrons; High resolution transmission electron microscopy; Mapping; Strain; Condenser systems; Dark field; Dark-field electron holographies; Differential phase; Differential phase contrast; Holographic technique; In-line holography; Numerical differentiation; Holograms; Article; controlled study; dark field electron holography; electron beam; holography; intermethod comparison; investigative procedures; microscope image; quantitative analysis; strain mapping; transmission electron microscopy

Domaines: Physique [physics]

Thibaud Denneulin, Florent Houdellier, Martin Hÿtch. Differential phase-contrast dark-field electron holography for strain mapping. Ultramicroscopy, 2016, 160, pp.98-109. ⟨10.1016/j.ultramic.2015.10.002⟩. ⟨hal-01723740⟩