Strain Measurements

• measurement of displacement fields by dark-field electron holography (DFEH)
• measurement of strain fields by nanobeam electron diffraction (NBED) and convergent beam electron diffraction (CBED)
• systematic investigation of dynamical diffraction effects at inhomogeneous displacement fields in electron beam direction
• comparison of dark-field phases and dark-field intensities with Howie-Whelan calculations
• determination of the three dimensional displacement field by means of dynamical diffraction
• studying the influence of relaxation effects of layered structures at specimen surfaces by means of DFEH and CBED

Electric Potential Measurements

• measurement of electrical potentials by off-axis electron holography
• measurement of electric fields by differential phase contrast (DPC)
• reliable and accurate determination of polarization fields
• investigation of biased pn-junctions by means of DPC and off-axis holography

L. Meißner, T. Niermann, D. Berger, and M. Lehmann;
Dynamical diffraction effects on the geometric phase of inhomogeneous strain fields;
Ultramicroscopy 207 (2019), 112844; DOI: 10.1016/j.ultramic.2019.112844

T. Niermann, L. Niermann, M. Narodovitch, and M. Lehmann;
Accuracy of polarization field measurements by electron holography in InGaN quantum wells;
Phys. Rev. B 103 (2021), 075306, DOI: 10.1103/PhysRevB.103.075306

L. Niermann;
Untersuchung und Anwendung der dynamischen Beugung an inhomogenen Verschiebungsfeldern in Elektronenstrahlrichtung in Halbleiterheterostrukturen;
Dissertation Technische Universität Berlin (2021); DOI: 10.14279/depositonce-11310