Highlights
Dec 20, 2006
Stanford University
Patterning of Large Arrays of Organic Semiconductor Single Crystals
Alejandro L. Briseno1,2, Stefan C.B. Mannsfeld1, Mang M. Ling1, Shuhong Liu1, Ricky J. Tseng2, Colin Reese1, Mark E. Roberts1, Yang Yang2, Fred Wudl2, Zhenan Bao1 1. Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA 2. Department of Chemistry and Biochemistry and Exotic Materials Institute, Department of Materials Science and Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA
Field-effect transistors made of single organic crystals are ideal for studying the charge transport characteristics of organic semiconductor materials. Their outstanding device performance, relative to that of transistors made of organic thin films, makes them also attractive candidates for electronic applications such as active matrix displays and sensor arrays. The only approach currently available for creating single crystal devices is manual selection and placing of individual crystals—a process prohibitive for producing devices at high density and with reasonable throughput.
Dec 15, 2006
University of Wisconsin - Madison
A New Organic-Inorganic Heterojunction: GaN-Pentacene
Organic semiconductor materials have shown promise in recent years for use in low-cost electronics applications such as photovoltaics, chemical sensors, and flat-panel displays. In particular, pentacene thin films have been shown to exhibit high a large field-effect mobility on the order of 1 cm2/Vs, which is sufficient for organic thin-film transistors (TFTs) for displays.
Dec 7, 2006
University of Nebraska - Lincoln
Light Used as a Magnetic Hammer
Roger Kirby Group (Nebraska MRSEC)
Scientists in the University of Nebraska MRSEC are using very short light pulses from a femtosecond laser to perturb magnetic materials and to probe their behavior at times after the perturbation. The light pulses are only about 100 millionth-billionths of a second long.
Dec 6, 2006
California Institute of Technology
Active Nanophotonic Materials and Devices
The recent decade has seen an explosion of optical communication. Yet much of the information processing is conducted electronically since there have been few truly tunable optical devices. Ferroelectric materials offer a potential solution. They possess interesting nonlinear properties that can be used to design and fabricate unique active tunable nanophotonic devices. Photonic crystals are synthetic hetero-structures that provide an unprecedented ability to manipulate light including slowing down and reflecting selected frequencies.
Dec 4, 2006
Microtubules in Capped Channels: The Persistence of Circulation
In eukaryotic cells, kinesin motor proteins transport intracellular cargo along microtubules, 25 nm protein filaments that form the cell cytoskeleton. This biomotor transport system is of fundamental importance in cell function and dysfunction, and provides a model system for nano- and microscale transport in engineered systems.
Dec 4, 2006
Pennsylvania State University
Catalytic Pumping: Electrokinesis arrested
In 2004, a Penn State MRSEC team showed that bimetallic platinum/gold nanorods could swim at speeds up to 20 microns per second by catalyzing the decomposition of hydrogen peroxide. Nickel stripes added to the motors allowed them to be steered using weak magnetic fields as a "remote control". Microgears formed from platinum and gold rotated in hydrogen peroxide solutions. In 2005, MRSEC researchers†have inverted the system: instead of moving catalytic structures through a static solution, a static silver/gold catalytic structure pumps the solution past it.
Dec 4, 2006
Pennsylvania State University
Magnetic Frustration by Design: Spins Can't Always Get What They Want
Frustration is not only a state of mind, but also a state of matter wherein the interactions among different subunits cannot all be satisfied. Ordinary water ice is highly frustrated: there are many many different ways in which the protons within the lattice of ice can be arranged, and all are equally good (or bad, depending on your point of view).
Dec 4, 2006
Pennsylvania State University
Molecular Rulers: A Marriage of Molecules and Metal
Molecules come in well-defined lengths: Penn State MRSEC researchers have invented a technique called "Molecular Rulers," in which molecular layers of precisely defined widths coat preexisting structures and form templates for patterning new structures with ever-smaller dimensions. Advanced lift-off processing and new bilayer resists, developed in 2005, have dramatically improved the uniformity and sharpness of the nanometer-scale gaps between the parent and daughter structures. These gaps can be tailored with molecular scale precision.
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