The Triebenberg Laboratory belongs to the consortium of ESTEEM2, the European network of Transmission Electron Microscopy for Materials Science. ESTEEM2 offers free access to the most powerful TEM installations in Europe.

Electron Microscopy - A journey into Nano-Cosmos
Transmission Electron Microscopes (TEMs) are very powerful instruments. They provide magnification over a range of about five decades. The best instruments reach resolutions sufficient for resolving the atomic structure of condensed matter.

Electron Holography
Since its foundation the Triebenberg Lab has a strong focus on Electron Holography, making it one of our main areas of expertise. Electron Holography was originally invented by D. Gabor (Nobel prize 1971) to overcome the resolution limits of conventional TEM. Since then it became a powerful technique for exploring the quantum world. It has also been developed into a versatile advanced TEM technique with numerous applications (see below) in material science.

Dopant Profiling of Semiconductor Devices
The functionality of semiconductor devices is given by the distribution of implanted dopants. The induced local bandshift causes potential variations in the bulk material, which can be measured in phase images provided by Electron Holography. With continuously increasing miniaturisation, Electron Holography has become a powerful analysis tool for the industry.

Strain mapping in semiconductor devices
Introduction of strained silicon technology allows an incredible performance boost and significant efficiency improvements in many modern semiconductor devices. Consequently, semiconductor industry is looking for a new metrology tool that allows 2-dimensional strain mapping in semiconductor devices at nanometre scale resolution. Dark-field off-axis electron holography proves to be an excellent tool fulfilling the needs of semiconductor industry.

Magnetic field mapping
As a consequence of the Aharanov-Bohm effect the magnetic phase shift is proportional to the magnetic flux enclosed by the interfering trajectories of the electron beam. As a consequence of its interference principle off-axis electron holography is particularly suited to measure the magnetic phase shifts. In combination with the high-resolution capability of the TEM off-axis electron holography offers the unique possibility to measure magnetic fields with nm resolution over large fields of view.

Electron-holographic tomography
Intrinsic electrostatic and magnetic fields play a crucial role for the essential structure-property relation in emerging nanostructures. Electron-holographic tomography (EHT) in the TEM, combining off-axis electron holography (EH) with electron tomography (ET), provides an unique access to the field information, because it allows the quantitative 3D mapping of electrostatic potentials and magnetostatic vector fields with a resolution of a few (5-10) nanometers.

Inelastic Holography
The coherence of an electron wave is determined by the interaction process with an object. Especially the inelastic interaction inevitably leads to decoherence, which appears as specific attenuation of fringe contrast in off-axis electron holography. The evaluation of fringe contrast in dependence on the spatial distance of the superimposing electron beams and on energy transfer allows the reconstruction the coherence properties given by the scattering processes.  This approach provides principal access to the off-diagonal elements of the reduced beam electron density matrix.

Imaging simulation and ab-initio methods
Images obtained within Transmission Electron Microscopy deliver a direct impression of structure details of the specimen, like grain boundaries, defects, etc. However, a more comprehensive quantitative interpretation of images in terms of magnetic and electric fields, atomic species and energy loss spectra requires a detailed comparison with image simulations. The image simulations incorporate both the calculation of relativistic elastic and inelastic electron-specimen interactions, including the consideratin of the thermal motion of atoms, excitation of quasiparticles, etc, and the influence of the microscope like aberrations, transfer properties of the camera, etc. As the developement of modern TEM advances, reaching sub Angstrom special and sub eV energetic resolution by now, the applied theoretical models for the electron-specimen interaction have to include Density Functional Theory calculations to investigate properties, like electrostatic potentials, excited states and phonon dispersion. The theoretical investigation of the image formation within the microscope are including the calculation of lense properties, the influence of the biprim and the noise properties of the camera.

The list of examples, we are currently working at, is constantly changing. Particularly, the addressed problems of solid state physics are manifold and typically grow larger with each particular specimen put into the TEM. We therefor add a small list of additional working fields without claiming completeness.

  • Aberration Assessment and Correction
  • Cs-Corrected Electron Holography
  • Quantitative Electron Holography at Atomic Dimensions

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Anne Dressler-Benad
Letzte Änderung: 02.06.2016