Atomically Resolved Structure of Solid/Solid Interfaces

Summary

This project targets the determination of the atomically resolved structure and composition across buried interfaces applying transmission electron microscopy (TEM). Mainly Cs-corrected techniques will be used in combination with techniques that exploit inelastic signals. For the different interface formation processes and expected structures, several model systems will be studied, which will be chosen in close cooperation with the groups synthesizing materials.

Polar/non-polar as well as strained/lattice-matched interfaces in semiconductor heterostructures will be a thematic priority. GaP/Si as well as GaAs/Ge is chosen as a nearly lattice-matched system to study the influence of different crystal polarity on the interface formation mechanism. Using interfaces in the (GaIn)(NAsSb) heterostructure system, this knowledge can be correlated with the influence of strain as well as with the influence of metastability of material systems on the interface structure between two inorganic semiconductors. Our knowledge on TEM of radiation-sensitive organic samples will be developed further to image composite structures of layered with organic materials.

Electron scattering and diffraction will be theoretically described with a special focus on the achievable resolution at buried interfaces, taking into account thermally diffuse scattering as well as TEM specimen relaxation, using realistic crystal models, which are calculated by valence force field and density functional theory, as input parameters. The study of different model material systems will allow for a detailed understanding of different electron-matter interaction at interfaces of hybrid materials. From these data a quantitative understanding of the atomic arrangement at interfaces will be derived. This quantified interface structure is a prerequisite for the correlation to growth as well as to the optoelectronic properties of the studied materials.

Project-related publications

1. J.O. Oelerich, L. Duschek, J. Belz, A. Beyer, S.D. Baranovskii, K. Volz
   STEMsalabim: A high-performance computing cluster friendly code for scanning transmission electron microscopy image simulations of thin specimens
   Ultramicroscopy 177, 91 (2017).
2. L. Duschek, P. Kükelhan, A. Beyer, S. Firoozabadi, J.O. Oelerich, C. Fuchs, W. Stolz, A. Ballabio, G. Isella, K. Volz
   Composition determination of semiconductor alloys towards atomic accuracy by HAADF-STEM
   Ultramicroscopy 200, 84 (2019).
3. A. Beyer, L. Duschek, J. Belz, J.O. Oelerich, K. Jandieri, K. Volz
   Influence of surface relaxation of strained layers on atomic resolution ADF imaging
   Ultramicroscopy 181, 8 (2017).
4. S. Ahmed, M. Bianchini, A. Pokle, M.S. Munde, P. Hartmann, T. Brezesinski, A. Beyer, J. Janek, K. Volz
   Visualization of Light Elements using 4D STEM: The Layered‐to‐Rock Salt Phase Transition in LiNiO₂ Cathode Material
   Adv. Energy Mater. 10, 2001026 (2020).
5. A. Beyer, K. Volz
   Advanced Electron Microscopy for III/V on Silicon Integration
   Adv. Mater. Interfaces 6, 1801951 (2019).
6. A. Beyer, F.F. Krause, H.L. Robert, S. Firoozabadi, T. Grieb, P. Kükelhan, D. Heimes, M. Schowalter, K. Müller-Caspary, A. Rosenauer, K. Volz
   Influence of plasmon excitations on atomic-resolution quantitative 4D scanning transmission electron microscopy
   Sci. Rep. 10, 17890 (2020).