Non-thermal deposition of films and structures

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Glancing Angle Deposition/Olique Angle Deposition of Nanostructured, Highly Porous Thin Films

Fig. 1: Nanostructures prepared by GLAD/OAD can show a large variety of shapes. The morphology of the individual structures can be controlled e.g. by the substrate rotation speed (a – d), the substrate temperature (e), the angle of incidence (f, g), the azimuthal sample position (h), substrate pre-patterning techniques (i – k), and the used materials (l).
Fig. 2: (a) HR-TEM image of titanium nanostructures. Metallic GLAD/OAD nanostructures often grow single crystalline. (b) XRD{110} pole figure measurement of an obliquely deposited molybdenum film. The single crystalline nanostructures are well oriented and the film shows a biaxial texture.
Fig. 3: Computer simulations are a powerful tool to investigate the self-shadowing effect and evolutionary selection processes and thereby contribute to the understanding of the GLAD/OAD process. Shown here is a simulation of the growth of spiral structures without surface diffusion on a flat substrate. (Click for animation!)

The glancing angle deposition (GLAD) or oblique angle deposition (OAD) technique enables the growth of nanostructured, highly porous thin films composed of three-dimensionally separated, nano-sized structures. Characteristic for GLAD/OAD is that the incoming particle flux strikes the substrate surface under a highly oblique (“glancing”) angle. The resulting shadowing effects on the substrate, often combined with a rotation of the substrate around its normal, facilitate to control the shape of structures. GLAD/OAD can be realized by the common standard physical vapor deposition (PVD) techniques used in thin film technology. In principle, all materials that can be deposited by PVD methods (i.e. all inorganic materials including compounds as well as some organic molecules) can be used for the GLAD/OAD approach. Thin films fabricated by GLAD/OAD are applied, for instance, as substrates for biosensors that can selectively detect single molecules or isolated pathogens by surface-enhanced Raman spectroscopy. Besides applications of GLAD/OAD thin films, understanding the fundamentals of the GLAD/OAD growth processes is an important research topic.

Deposition technique variants

  • Electron-beam evaporation
  • Ion-beam sputtering

 

Selected publications

 

  • C. Grüner, I. Abdulhalim, B. Rauschenbach
    Glancing angle deposition for biosensing applications
    Encyclopedia of Interfacial Chemistry, Surf. Sci. Electrochem. 3 (2018) 129-137
    doi: 10.1016/B978-0-12-409547-2.14174-5

  • C. Grüner, S. Liedtke, J. Bauer, S.G. Mayr, B. Rauschenbach
    Morphology of thin films formed by oblique physical vapor deposition
    ACS Appl. Nano Mater. 1 (2018) 1370–1376
    doi: 10.1021/acsanm.8b00124

  • S. Liedtke, C. Grüner, J.W. Gerlach, B. Rauschenbach
    Comparative study of sculptured metallic thin films deposited by oblique angle deposition at different temperatures
    Beilstein J. Nanotechnol. 9 (2018) 954-962
    doi: 10.3762/bjnano.9.89

  • S. Liedtke, C. Grüner, A. Lotnyk, B. Rauschenbach
    Glancing angle deposition of sculptured thin metal films at room temperature
    Nanotechnology 28 (2017) 385604
    doi: 10.1088/1361-6528/aa7a79