AVS2014 Session SE-TuP: Advanced Surface Engineering Poster Session

Ion bombardment of polycrystalline thin metal films is known to induce nanometer-scale surface patterning, including ripples and dots^1,2. Additionally, the irradiation of metals with oxygen ions has been shown to induce surface oxidation, with a state dependence on fluence³. This work seeks to unravel the directed irradiation synthesis of oxide-based thin-films, in particular ZnO thin-films, with low-energy irradiation-driven mechanisms on dissimilar material substrates, such as polymer-based systems. This examines the dual effects of oxygen irradiation as a method of both oxidizing and patterning metal thin-films at ambient temperatures. This represents a scalable process in growing and functionalizing metal-oxide thin-films on polymers, which are sensitive to the high temperatures required in thermal oxidation processes. Ion-beam sputtering (IBS) is known to induce surface nanopatterning in multi-component systems⁴ with simultaneous modification of surface chemistry. Irradiation with O⁺ is performed at grazing incidence near 70° with particle energies between 25-1000 eV at ambient temperatures. X-ray photoelectron spectroscopy investigates the resulting oxidation states as a function of fluence from early-stage nanopattern formation near 10¹⁵ cm^-2 up to fluences nearing a coarsening regime. Atomic force microscopy examines pattern formation under similar conditions. These results are then adapted to nanostructured thin-films on flexible substrates, namely polydimethylsiloxane (PDMS) about 1-mm thick and 1-cm². The ability to fabricate heterostructures on transparent, flexible substrates offers exciting applications in areas such as gas sensors, biosensors, and photonics⁵. Additional benefits of an oxygen ion beam are the chemical changes (formation of SiO groups, introduction of water and gaseous byproducts) induced in the PDMS substrate as the active thin-film is nanostructured. Oxidation of this polymer has been shown to induce significant temporary hydrophilicity⁶ and thus provide for an effective bioactive nanostructured biointerface for in-situ endovascular protocols.

¹ D. Ghose, J. Phys. Condens. Matter 21, 224001 (2009).

² P. Gailly, C. Petermann, P. Tihon, and K. Fleury-Frenette, Appl. Surf. Sci. 258, 7717 (2012).

³ N. V. Alov, Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 256, 337 (2007).

⁴ O. El-Atwani, S. Ortoleva, A. Cimaroli, and J.P. Allain, Nanoscale Res. Lett. 6, 403 (2011).

⁵ I.-S. Hwang, Y.-S. Kim, S.-J. Kim, B.-K. Ju, and J.-H. Lee, Sensors Actuators B Chem. 136, 224 (2009).

⁶ H. Hillborg, J.F. Ankner, U.W. Gedde, G.D. Smith, H.K. Yasuda, and K. Wikstro, Polymer (Guildf). 41, 6851 (2000).