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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
401

Phase Behavior of Block Copolymers in Compressed CO2 and as Single Domain-Layer, Nanolithographic Etch Resists For Sub-10 nm Pattern Transfer

Chandler, Curran Matthew 01 September 2011 (has links)
Diblock copolymers have many interesting properties, which first and foremost include their ability to self-assemble into various ordered, regularly spaced domains with nanometer-scale feature sizes. The work in this dissertation can be logically divided into two parts - the first and the majority of this work describes the phase behavior of certain block copolymer systems, and the second discusses real applications possible with block copolymer templates. Many compressible fluids have solvent-like properties dependent on fluid pressure and can be used as processing aids similar to liquid solvents. Here, compressed CO2 was shown to swell several thin homopolymer films, including polystyrene and polyisoprene, as measured by high pressure ellipsometry at elevated temperatures and pressures. The ellipsometric technique was modified to produce accurate data at these conditions through a custom pressure vessel design. The order-disorder transition (ODT) temperatures of several poly(styrene-b-isoprene) diblock copolymers were also investigated by static birefringence when dilated with compressed CO2. Sorption of CO2 in each copolymer resulted in significant depressions of the ODT temperature as a function of fluid pressure, and the data above was used to estimate the quantitative amount of solvent in each of the diblock copolymers. These depressions were not shown to follow dilution approximation, and showed interesting, exaggerated scaling of the ODT at near-bulk polymer concentrations. The phase behavior of block copolymer surfactants was studied when blended with polymer or small molecule additives capable of selective hydrogen bonds. This work used small angle X-ray scattering (SAXS) to identify several low molecular weight systems with strong phase separation and ordered domains as small as 2-3 nanometers upon blending. One blend of a commercially-available surfactant with a small molecule additive was further developed and showed promise as a thin-film pattern transfer template. In this scenario, block copolymer thin films on domain thick with self-assembled feature sizes of only 6-7 nm were used as plasma etch resists. Here the block copolymer's pattern was successfully transferred into the underlying SiO2 substrate using CF4-based reactive ion etching. The result was a parallel, cylindrical nanostructure etched into SiO2.
402

Porous Metal Oxide Materials Through Novel Fabrication Procedures

Hendricks, Nicholas 01 September 2012 (has links)
Porous metal oxide materials, particularly those comprised of silica or titania, find use in many applications such as low-k dielectric materials for microelectronics as well as chemical sensors, micro/nanofluidic devices, and catalyst substrates. For this dissertation, the focus will be on the processing of porous metal oxide materials covering two subjects: hierarchical porosity exhibited over two discrete length scales and incorporation of functional nanomaterials. To generate the porous silica materials, the technique of supercritical carbon dioxide infusion (scCO2) processing was heavily relied upon. Briefly, the scCO2 infusion processing utilizes phase selective chemistries within a pre-organized amphiphilic block copolymer template using scCO2 as the reaction medium to selectively hydrolyze and condense silica precursors to yield mesoporous materials. To further develop the scCO2 infusion processing technique, hierarchically porous silica materials were generated on unique substrates. Hierarchically structured silica nanochannels were created using a combination of scCO2 infusion processing and nanoimprint lithography (NIL) patterned sacrificial polymer templates to yield mesopores and airgap structures respectively. Hierarchically porous silica materials were also generated on alternative substrates, in the form of cellulose filter paper, which were used to host the amphiphilic block copolymer template to yield tri-modal porosity silica materials. To extend the applicability of mesoporous silica generated from scCO2 infusion processing, functional nanomaterials, in the form of pre-synthesized gold nanoparticles, fullerene derivatives, and polyhedral oligomeric silsequioxanes (POSS) were embedded within the mesoporous silica to produce unique composite materials. The functional nanomaterials were able to impart specific properties, typically only affored to the functional nanomaterials, upon the mesoporous silica thin film with an example being enhanced thermal and hydrothermal properties of mesoporous silica doped with POSS molecules. To continue research with functional nanomaterials, nanoparticle composite materials, comprised of crystalline metal oxide nanoparticles and binder/filler materials, either organic or inorganic, were also evaluated as novel NIL resist materials. Patterning of the nanoparticle composite materials, specifically, but not limited to, titanium dioxide based materials, into two dimensional, arbitrarily shaped, sub-micron features was readily achieved on either rigid or flexible substrates. True three-dimensional structures, based on nanoparticle composite materials, were fabricated by utilizing release layers and pre-patterned substrates.
403

Fabrication and imaging of highly ordered plasmonic Au nano-prism and self-assembled supramolecular nanostructure

Ayinla, Ridwan Tobi 08 August 2023 (has links) (PDF)
The precise control of the resonance frequency of plasmonic nanostructures is critical and depends on the size, composition, shape, and dielectric nature of the environment. The ability to control the shape and size of nanomaterials acutely depends on the fabrication technique and material design. We used a cheap and scalable method known as nanosphere lithography (NSL) to fabricate plasmonic nano-prism (NP) on glass and indium tin oxide substrate (ITO). The methods involve substrate hydrophilicity treatment, polystyrene nanosphere masking, metal deposition, and mask removal. The array and specific morphology of the fabricated NP was established using scanning electron microscope (SEM) and atomic force microscope (AFM). Finally, we used UVVis spectroscopy to determine the plasmonic resonance frequencies of fabricated NP on different substrates. The results reported herein have potential applications in surface-enhanced Raman spectroscopy (SERS), and biosensing. We also used scanning tunneling microscope to obtain high spatial resolution images of supramolecular trigrams.
404

Laser Plasma Radiation Studies For Droplet Sources In The Extreme Ultraviolet

Kamtaprasad, Reuvani 01 January 2010 (has links)
The advancement of laboratory based Extreme Ultraviolet (EUV) radiation has escalated with the desire to use EUV as a source for semiconductor device printing. Laser plasmas based on a mass-limited target concept, developed within the Laser Plasma Laboratory demonstrate a much needed versatility for satisfying rigorous source requirements. This concept produces minimal debris concerns and allows for the attainment of high repetition rates as well as the accommodation of various laser and target configurations. This work demonstrates the generation of EUV radiation by creating laser plasmas from mass-limited targets with indium, tin, and antimony doped droplets. Spectral emission from the laser plasmas is quantified using a flat-field spectrometer. COWAN code oscillator strength predications for each of the dopants were convolved with narrow Gaussian functions creating synthetic spectra for the EUV region between 10 nm - 20 nm. A preliminary comparison was made between the theoretical spectra and experimental results. From this comparison, ion stage transitions for each of the hot dense plasmas generated were assessed.
405

Surface Microtopography Modulation of Biomaterials for Bone Tissue Engineering Applications

Kim, Eun Jung 04 June 2010 (has links)
No description available.
406

SINGLE MOLECULE ELECTRONICS AND NANOFABRICATION OF MOLECULAR ELECTRONIC DEVICES

Rajagopal, Senthil Arun 15 August 2006 (has links)
No description available.
407

THE FABRICATION OF A PHOTONIC CRYSTAL BASED THREE CHANNEL WAVELENGTH DIVISON DEMULTIPLEXER (WDDM) DEVICE

Cao, Siwei 28 August 2008 (has links)
No description available.
408

Phase Separation of Polymer-grafted Nanoparticle blend Thin Films

Zhang, Yue, Zhang January 2017 (has links)
No description available.
409

Photonic Devices Fabricated with Photonic Area Lithographically Mapped Process

Zhou, Yaling 21 April 2009 (has links)
No description available.
410

PIEZOELECTRIC POLYMER MICROSTRUCTURES FOR BIOMEDICAL APPLICATIONS

Koucky, Michael Harten 26 June 2009 (has links)
No description available.

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