Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 18: Micro- and Nanopatterning (jointly with O)

DS 18.5: Talk

Wednesday, March 13, 2013, 10:30–10:45, H8

Nickel Nanodot Arrays on Silicon formed by Nanosphere Lithography: A TEM Study — •Johannes Pauly and Jörg K. N. Lindner — Department of Physics, University of Paderborn, 33098 Paderborn, Germany

Nanosphere lithography (NSL) is a cost-effective bottom-up technique to form equally sized nanodots on surfaces, which can be easily scaled up to large areas. It is based on the self-organized arrangement of colloidal nanospheres in a hexagonally close packed monolayer which serves as a shadow mask for a subsequent thin film deposition process. The lateral size of nanodots and their density depend on the diameter of spheres, while the exact shape of dots depends on the deposition method and the dot/substrate combination used. This is due to the fact that the deposition technique defines the angular distribution of atoms arriving at the sample and the dot/substrate materials combination determines the crystallization and wetting properties of the dots. In addition the clogging of masks strongly affects the growth of dots. While in previous studies mostly scanning electron and atomic force microscopy were used to image dots, in the present study transmission electron microscopy is used to characterize the shape and structure of dots. To this end nanosphere masks of several square centimetre size were prepared on silicon using a doctor blade technique and an aqueous suspension of polystyrene spheres. Nickel thin films were deposited by thermal evaporation at room temperature. It is shown that nanocrystalline triangular Ni dots with extremely sharp tips are formed, the radius of tip curvature being given by the size of Ni grains.