Magnetic Field Applied to 3D Manipulation of Alloys
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were determined by high-resolution transmission electron microscopy to be conformal, uniform, continuous, and dense, with a controllable thickness between a few Ångstroms and a few nanometers. After drying the samples for 4 h at 150°C, the team then used them to fabricate DSSCs. While niobia coatings did not improve the
High Modulus Fluorinated Molding Materials Improve Fidelity in Soft Lithography Molding materials used for soft lithography, a nanofabrication technique, just got a little tougher. Polydimethylsiloxane (PDMS) elastomers, typically used as a molding material to replicate feature sizes greater than 100 nm, tend to have a low elastic modulus (2.0 MPa) and low surface energy (~25 mN/m). These properties make it easy to remove the PDMS from delicate master templates. New findings, however, show that increasing a material’s elastic modulus may help improve pattern transfer fidelity, especially when replicating high aspect ratio features with small spacing or periodicity. A research team in cluding S.S. Williams and coresearchers at the University of North Carolina at Chapel Hill, S. Retterer at Oak Ridge National La boratory, R. Ruiz of Hitachi Global Storage Technologies, and J.M. DeSimone at the University of North Carolina at Chapel Hill and North Carolina State University reported in the April 14 issue of Nano Letters (DOI: 10.1021/nl100326q; p. 1421) a composite molding technique that utilizes perfluoropolyether-(PFPE)-based elastomers. Williams and colleagues found that by increasing the modulus of the PFPE, smaller feature sizes could be replicated than when molds were made with PDMS.
Magnetic Field Applied to 3D Manipulation of Alloys The relentless drive toward increased miniaturization and better performance of microelectronic devices has necessitated three-dimensional (3D) architectures with vertical geometries. Such 3D architectures require stacked two-dimensional layers formed by photolithography or perpendicular vias for the conductive pathways. Various new approaches have been proposed to obtain such structures, including self-assembly and ink-jet printing; however, these use processes and
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cell performance, cells based on electrodes with amorphous titania coatings were up to 65% more efficient than non-coated reference cells, and bi-layer titania/magnesia coatings led to up to 113% efficiency gains. The researchers attributed the enhancements to improved inter-particle connections from the titania layer and reduced
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recombination rates due to the insulating properties of the magnesia layer. These results suggest that enhanced DSSCs fabricated by a low-cost, lowtemperature technique may one day offer a competitive alternative to conventional silicon photovoltaics. COLIN MCCORMICK
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Figure 1. Trimethylolpropyl triacrylate (TMPTA) patterns formed using a variety of composite molds. TMPTA patterns made with molds composed of a low modulus material (1.4 K perfluoropolyether, PFPE) (a) demonstrated a loss in resolution while TMPTA patt
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