Ion-induced nanopatterning of crystalline surfaces for applications in bottom-up nanostructure fabrication

Nanostructured materials will be key components in future technological solutions of our society’s present challenges: They can enhance the efficiency of energy harvesting from renewable sources, increase the sensitivity of diagnostical tools in medicine, or enable novel information technology. For making substantial contributions to these fields by applying nanostructured materials, we must be able to fabricate them easily and reproducibly on industrially relevant scales. This can be achieved by the bottom-up approach of templated growth on substrates nanopatterned by ion irradiation: The required technologies of low-energy ion irradiation, polymer chemistry, and physical vapor deposition are well-established.
In this contribution, we outline the mechanism of self-assembly of vacancies and adatoms on crystalline semiconductor surfaces induced by low-energy ion irradiation [1,2]: At temperatures above the material’s recrystallization temperature, the substrate crystallinity is retained. Thus, diffusion of vacancies and adatoms on the surface is highly anisotropic, which leads to the formation of surface nanopatterns reflecting the crystal symmetry of the substrate material. The various resulting pattern morphologies and the influence of external process parameters will be presented. We hope to initiate discussion and collaboration by highlighting potential applications based on these ion-induced nanopatterns, such as growing epitaxial nanowire arrays by shadowing effects at oblique incidence deposition, or inducing long-range order in copolymer thin films to fabricate chemically nanopatterned templates for nanostructure growth [3].

Acknowledgement
We thank K. Potzger and A. Henschke (HZDR) for their support in MBE for templated nanowire growth.

References
[1] X. Ou et al., Nanoscale 7, 18928 (2015)
[2] Q. Jia et al., Nano Research 15, 1 (2017)
[3] D. Erb et al., Science Advances 1, e1500751 (2015)