Development of splitting convergent beam electron diffraction (SCBED)

Florent Houdellier (1) , Falk Röder (1) , Etienne Snoeck (1)

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

Using a combination of condenser electrostatic biprism with dedicated electron optic conditions for sample illumination, we were able to split a convergent beam electron probe focused on the sample in two half focused probes without introducing any tilt between them. As a consequence, a combined convergent beam electron diffraction pattern is obtained in the back focal plane of the objective lens arising from two different sample areas, which could be analyzed in a single pattern. This splitting convergent beam electron diffraction (SCBED) pattern has been tested first on a well-characterized test sample of Si/SiGe multilayers epitaxially grown on a Si substrate. The SCBED pattern contains information from the strained area, which exhibits HOLZ lines broadening induced by surface relaxation, with fine HOLZ lines observed in the unstrained reference part of the sample. These patterns have been analyzed quantitatively using both parts of the SCBED transmitted disk. The fine HOLZ line positions are used to determine the precise acceleration voltage of the microscope while the perturbed HOLZ rocking curves in the stained area are compared to dynamical simulated ones. The combination of these two information leads to a precise evaluation of the sample strain state. Finally, several SCBED setups are proposed to tackle fundamental physics questions as well as applied materials science ones and demonstrate how SCBED has the potential to greatly expand the range of applications of electron diffraction and electron holography. © 2015 Elsevier B.V..

Mots clés: Electron diffraction; Electron holography; Electron optics; Holographic interferometry; Lanthanum compounds; Probes; Strain measurement; Acceleration voltages; Applied materials; Back focal planes; Convergent beam electron diffraction (CBED); Convergent beams; Epitaxially grown; Fundamental physics; Si/SiGe multi-layer; Electrons; Article; dark field electron holography; electron diffraction; finite element analysis; holography; illumination; molecular dynamics; process development; quantitative analysis; Raman spectrometry; simulation; splitting convergent beam electron diffraction; transmission electron microscopy

Domaines: Physique [physics]

Florent Houdellier, Falk Röder, Etienne Snoeck. Development of splitting convergent beam electron diffraction (SCBED). Ultramicroscopy, 2015, 159 (P1), pp.59-66. ⟨10.1016/j.ultramic.2015.08.002⟩. ⟨hal-01723741⟩