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Title:Fabrication of metal-oxide thin-films and features on dissimilar materials via ion-assisted codeposition
Author(s):Koyn, Zachariah Taylor
Advisor(s):Allain, Jean Paul
Contributor(s):Zhang, Yang
Department / Program:Nuclear, Plasma, & Rad Engr
Discipline:Nuclear, Plasma, Radiolgc Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Ion beam
flexible substrate
zinc oxide
plasma nanosynthesis
Abstract:The merging of metal oxides and polymers has a number of interesting potential applications that rely on the wettability, optical, and electronic properties of the surface. One challenge in the fabrication of these dissimilar materials is that the heat often used to create oxide nanostructures results in the thermal decomposition of the polymer. This requires creative approaches to successfully merge these materials. Many current approaches involve the separate creation of metal oxide nanostructures, followed by some process of embedding them in an uncured polymer. Previous work has shown that ion beams have been used to sputter deposit metals, pattern polycrystalline metals, controllably oxidize metal surfaces, and induce chemical changes in the surfaces of polymers. Presented here is a single step technique that draws on these, utilizing dual ion beams to deposit, oxidize, and pattern Zn on Si and PDMS. Two ion beams are installed in a perpendicular configuration, with one normal to the substrate surface and the other parallel. The parallel beam passes over the substrate and impinges on a Zn target, sputter depositing the material onto the substrate. Simultaneously, the normal incidence beam impinges on the substrate surface, imparting energy and sputtering both the substrate material and the deposited Zn. The effects of changing the ion beam flux ratio (0.1-2.0), energy (500 eV and 1000 eV), species (Ar+ and O2+ for substrate irradiation, Ar+ for sputter deposition), and fluence (1E17 ions/cm2 and 5E17 ions/cm2) are examined. These factors allow for the comparison of different deposition rates, chemical effects, and surface evolution stages in the synthesis of these functionalized surfaces. Surfaces are characterized by several ex-situ techniques: topography (AFM), chemistry (XPS), and wettability (static contact angle). This technique has yielded a number of interesting surfaces. On Si, the formation of nanodots is seen under many processing parameters. These dots have no ordering, but their size (~20-100 nm diameter) and spatial density (1-100’s um-2) can be controlled by the flux ratio and ion energy. The codeposition on Si at higher total fluence is also shown to induce ripples in the Si surface in addition to the formation of nanodots, as is expected from normal incidence irradiation with the presence of small amounts of surface impurities. XPS has shown that the flux ratio can finely tune the amount of Zn deposited on the surfaces. On PDMS, all cases of irradiation, both with and without codeposition, have results in larger scale wrinkles to form on the surface (wavelength ~500-1000 nm) that are similar to previous work with oxygen plasma immersion. Notably, these are created with both O2+ and Ar+ ion beams. Atop this structure, the formation of nanodots is also seen. Again, these are not shown to have spatial ordering, but are larger than those seen on Si, ~75-200 nm diameter. These form at fewer combinations of processing parameters and are seen to preferentially grown in the valleys of the wrinkle pattern, specifically as they get larger. The ability to control the size and density of nanodots on PDMS with processing parameters is less clear than on Si. This work represents a relatively fast, scalable, low-temperature, single-step process to grow and functionalize metal-oxide nanostructures on polymers. The ability to functionalize flexible, transparent substrates with metal-oxide nanostructures offers exciting applications in areas such as flexible and wearable electronics, gas sensors, biosensors, and photonics.
Issue Date:2016-12-02
Rights Information:Copyright 2016 Zachariah Koyn
Date Available in IDEALS:2018-08-14
Date Deposited:2016-12

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