Pattern formation by self-organization

Pattern formation by self-assembly occurs in various systems – geological, biological, physical – and thus on various length scales. We study self-organization which is induced by ion irradiation of surfaces and results in nanoscale pattern formation on these surfaces.
Numerous nanoscale mechanisms of erosion and diffusive as well as ballistic mass redistribution occur simultaneously on a surface subject to ion irradiation. Each of these mechanisms in itself can act on the surface in a smoothing or in a destabilizing manner, depending on external parameters. The formation of nanoscale structures of different shape and regular arrangement can result from the interplay of these mechanisms. Via readily accessible external parameter such as surface temperature, ion mass and energy, or ion incidence angle we can determine which mechanisms act dominantly and thereby steer the pattern formation process.

Further information

Research Topics

We work both on fundamental questions in ion-induced pattern formation and on potential applications of the resulting nanostructured surfaces:

Ion-induced pattern formation is a multifactorial process and there are different approaches to its theoretical description. By means of systematic experimental studies and numerical simulations we strive to contribute to deepen the understanding of this complex self-assembly process. Open questions concern for instance the material-dependent differences in pattern symmetry, the existence of varying structure morphologies depending on the irradiation parameters, the dynamics of pattern formation, the shape and development of patterning defects, or the pattern formation in materials of complex composition or crystal structure.

By means of physical vapour deposition we can prepare nanostructured materials such as arrays of nanowires on ion-patterned surfaces in a bottom-up fashion. We study their shape-induced magnetic, optical, electric, or thermoelectric properties.

Methods: experiment and simulation

We prepare ion-induced nanostructure patterns via large-area irradiation with low-energy noble gas ions. Our setup offers ion energies ranging from 250 to 1200 eV with ion fluxes up to 5x10¹⁵cm^-2s^-1, polar ion incidence angles from 0 to 90°, and sample heating up to 600 °C for samples of up to 10 mm x 10 mm.

We operate a Bruker Multimode8 instrument for surface characterization via AFM. Moreover, we use GISAXS and XPCS as users of the NSLS-II for in-situ experiments on the dynamics of ion-induced patterning.

We use a continuum equation approach to theoretically describe the pattern morphologies resulting from ion irradiation and to simulate their development via numerical integration. Out MATLAB code for such simulations is available from us on request.

Offer for external researchers

Being part of the HZDR Ion Beam Center, we offer low-energy ion irradiation for surface modification also to external users.
Please get in touch with us!

Theses

On the research topics described above, we continuously offer projects for B.Sc., M.Sc., and PhD theses (the latter subject to funding availability) for students of physics. Please get in touch with us!

Current cooperations

• Theory of ion-induced pattern formation
  • Mark R. Bradley, Colorado State University
  • Daniel A. Pearson, PennState Abington

• Growth of catalytically active nanostructures on ion-beam patterned surfaces
  
  • Aram Bugaev, Paul-Scherrer-Institute

• Shape-induced magnetic properties
  • Oleksii Volkov, HZDR
• Adsorption of polymers and biomaterials on nanopatterned surfaces
  • Adrian Keller, University of Paderborn
  • Felix Plamper, TU Bergakademie Freiberg

Selected publications

• D.J. Erb, D.A. Pearson, T. Skeren, M. Engler, R.M. Bradley, S. Facsko: Intermediate morphology in the patterning of the crystalline Ge(001) surface induced by ion irradiation. Physical Review B 109(2024), 045439
  10.1103/PhysRevB.109.045439
• B.K. Pothineni, S. Kollmann, X. Li, G. Grundmeier, D.J. Erb, A. Keller: Adsorption of Ferritin at Nanofaceted Al2O3 Surfaces. Int. J. Mol. Sci. 24 (2023) 12808
  10.3390/ijms241612808
• D. Steinbach, R. Neubert, S. Gersdorf, C. Schimpf, D.J. Erb, D. Rafaja, F.A. Plamper, F. Mertens: Morphology and orientation change of layer-by-layer deposited one- and two-dimensional coordination polymer nanocrystals containing rhodium paddle-wheel units. Cryst. Eng. Comm. 25 (2023) 4568
  10.1039/d3ce00721a
• T. Weinert, R. Hübner, S. Facsko, D.J. Erb: Bottom-up fabrication of FeSb₂ nanowires on crystalline GaAs substrates with ion-induced pre-patterning. Front. Phys. 11:1149608 (2023)
  10.3389/fphy.2023.1149608
• D.J. Erb, J. Perlich, S. Roth, R. Röhlsberger, K. Schlage: Real-Time Observation of Temperature-Induced Surface Nanofaceting in M-Plane α-Al₂O₃. ACS Applied Materials and Interfaces 14 (2022) 27, 31373-31384.
  10.1021/acsami.1c22029
• D.J. Erb, P. Myint, K. Evans-Lutterodt, K. Ludwig, S. Facsko: In-situ GISAXS observation of ion-induced nanoscale pattern formation on crystalline Ge(001) in the reverse epitaxy regime. Phys. Rev. B 104 (2021) 235434.
  10.1103/PhysRevB.104.235434
• T. Seidel: Charakterisierung von thermoelektrischen Nanostrukturen auf Substraten mit ioneninduzierter Vorstrukturierung. Diplomarbeit TU Dresden (2021)
• P. Myint, D.J. Erb, X. Zhang, L. Wiegart, Y. Zhang, A. Fluerasu, R.L. Headrick, S. Facsko, K.F. Ludwig: Measurement of Ehrlich-Schwoebel barrier contribution to the self-organized formation of ordered surface patterns on Ge(001). Phys. Rev. B 102 (2020) 201404(R)
  10.1103/PhysRevB.102.201404
• D.J. Erb, R. de Schultz, A. Ilinov, K. Nordlund, R. M. Bradley, S. Facsko: Nanopatterning of the (001) surface of crystalline Ge by ion irradiation at off-normal incidence: Experiment and simulation. Phys. Rev. B 102 (2020) 165422
  10.1103/PhysRevB.102.165422
• R. de Schultz: Ion-Induced Surface nanostructures of Germanium(001), Masterarbeit TU Dresden (2018)
• G. Malsch: Untersuchung der topologischen Defekte in Oberflächenstrukturen auf GaAs und InAs unter niedrig-energetischem Ionenbeschuss, Masterarbeit TU Dresden (2017)
• D. Gkougkou, Polarization- and Wavelength-Dependent Surface-Enhanced Raman Spectroscopy Using Optically Anisotropic Rippled Substrates for Sensing, ACS Sensors 1 (2016) 318-323
  10.1021/acssensors.5b00176
• D. K. Ball, K. Lenz, M. Fritzsche, G. Varvaro, S. Günther, P. Krone, D. Makarov, A. Mücklich, S. Facsko, J. Fassbender, M. Albrecht, Magnetic properties of granular CoCrPt:SiO2 thin films deposited on GaSb nanocones, Nanotechnology 25 (2014) 085703
  10.1088/0957-4484/25/8/085703
• X. Ou, K.-H. Heinig, R. Hübner, J. Grenzer, X. Wang, M. Helm, J. Fassbender, S. Facsko, Nanoscale 7 (2015) 18928
  10.1039/c5nr04297f
• X. Ou, A. Keller, M. Helm, J. Fassbender, S. Facsko, Reverse Epitaxy of Ge: Ordered and Faceted Surface Patterns, Phys. Rev. Lett. 111 (2013) 016101
  10.1103/PhysRevLett.111.016101
• A. Keller, S. Facsko, R. Cuerno, Numerical Integrator for Continuum Equations of Surface Growth and Erosion, in: Computational Nanotechnology, edited by S. M. Musa (CRC Press, 2013), pp. 1–27
• A. Keller and S. Facsko, Ion-Induced Nanoscale Ripple Patterns on Si Surfaces: Theory and Experiment, Materials 3 (2010) 4811 – 4841
  10.3390/ma3104811
• S. Facsko, T. Dekorsy, C. Koerdt, C. Trappe, H. Kurz, A. Vogt, H. L. Hartnagel, Formation of Ordered Nanoscale Semiconductor Dots by Ion Sputtering, Science 285 (1999) 1551 - 1553
  10.1126/science.285.5433.1551