Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session K11: SPS Undergraduate Research IV |
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Chair: Thomas Olsen, American Institute of Physics Room: Maryland C |
Sunday, February 14, 2010 3:30PM - 3:42PM |
K11.00001: Carbide Derived Carbon Super Capacitor Application James Appelgate, Dave Bauer, James Quirin, S.E. Lofland, J.D. Hettinger, M. Heon, Y. Gogotsi Supercapacitors can be applied into many different fields from nano-robots to high density energy storage. Growing TiC films from a know recipe and removing the transition metal element, Titanium, by chlorination leaves a carbon film that can then be applied as an electrode in a super capacitor. The problem is when the Titanium is removed from the film the stress induced by this process causes the films to fracture into isolated islands. The islands allow electrons to travel across them every easily, but there is no transfer of electrons from island to island. We present results of an investigation of a technique control the location of the fractures and use them to our benefit. Ideally, we want to create them to fracture in parallel lines. To force these fractures into straight lines we will purchase substrates with thermal SiO$_{2}$ created on the surface of Si. Using an etching process we will removed a channel of SiO$_{2}$ the same as the thickness of the TiC film we plan on growing. These channels will allow the fractures to form in a correlated way creating a straight line. [Preview Abstract] |
Sunday, February 14, 2010 3:42PM - 3:54PM |
K11.00002: Investigation of Defect Formation in Multi-layer Graphene under Radioactive Irradiation Pubudu Galwaduge, Joseph Lambert, Roberto Ramos Graphene is a two-dimensional crystal experimentally observed in its free standing form a few years ago. With a record-high electron mobility, it has been suggested as a replacement for silicon in the fabrication of electronic devices. Electronic devices such as superconducting transistors and room temperature single electron transistors have been fabricated using graphene. In addition, it has been demonstrated that energetic particles such as electrons and ions can cause defect formation on graphene. We propose to study defect formation on graphene and graphite under radioactive irradiation using Raman Spectroscopy. We also report on the progress of measuring electronic transport properties using four probe lock-in measurements. [Preview Abstract] |
Sunday, February 14, 2010 3:54PM - 4:06PM |
K11.00003: Microscopic Thoery of the Conductivity in Carbon Nanotubes Seongphill Moon, Shigei Fujita, Akira Suzuki, S. Godoy The electrical conductivity of carbon nanotubes varies, depending on the temperature and the radius and pitch of the sample. In majority cases, the resistance decreases with increasing temperature, suggesting a thermally activated process. The standard band theory based on the Wigner-Seitz(WS) cell model predicts a gapless semiconductor, which does not account for the thermal activation. A new band model in which an ``electron'' (``hole'') has a carbon hexagon size for graphene is proposed. The normal charge carriers in graphene transport are ``electrons'' and ``holes.'' The ``electrons'' (``holes'') wavepackets extend over the carbon hexagon and carry the charges --e(+e). ``Electrons'' or ``holes'' thermally activated are shown to generate the observed temperature behavior of the conductivity in the nanotubes. [Preview Abstract] |
Sunday, February 14, 2010 4:06PM - 4:18PM |
K11.00004: Modeling optoelectronic devices incorporating colloidal quantum dots Ian Rousseau We present a computational model that explains operation of LEDs and solar cells incorporating amorphous semiconductors as transport layers and films of colloidal quantum dots as the optically active layers. The material parameters in the model can be determined experimentally. The model breaks the problem down into pieces and applies approximations taught in undergraduate-level physics to explain device operation. [Preview Abstract] |
Sunday, February 14, 2010 4:18PM - 4:30PM |
K11.00005: Nonlinear Optical Properties of Quantum Dot Composites Anthony Kolodzinski As novel nanoscale materials become more integral to technological advances, a deeper understanding of their fundamental properties is required. A quantum dot is a semiconductor particle fabricated from various materials and at various sizes on the nanometer scale. Our experiments aim to understand the nonlinear optical properties of quantum dot composites, which will pave the way for applications in lithography, optical computing, optical communications, and solar technology. In order to experimentally observe nonlinear optical effects we use a standard Z-scan as our main technique. We use a nanosecond pulsed laser with its beam split. One beam goes to a reference detector while the other is directed through a lens, sample of quantum dot composite, and an aperture. We then move the sample through the beam's focus, and measure the beam's final energy. With the aperture open we measure nonlinear photon absorption, but when it is closed we measure nonlinear diffraction. Our current research involves testing the nonlinear optical properties of liquid composites of CdSe particles suspended in toluene. However, we hope to expand our research to samples of solid composites of different chemical compositions and sizes. [Preview Abstract] |
Sunday, February 14, 2010 4:30PM - 4:42PM |
K11.00006: Fabricating Flux Qubits With Electron Beam Lithography Erik Crowe, A.J. Przybysz, H. Kwon, B.K. Cooper, R. Budoyo, K. Mitra, C.J. Lobb, J.R. Anderson, A. Dragt, F.C. Wellstood, V. Zaretski, Z. Kim, B. Palmer We will present work on fabricating an Al/AlO$_{x}$/Al flux qubit on a sapphire substrate. The device consists of a rectangle SQUID loop with an area of 5 $\mu $m x 10 $\mu $m, where one third of the loop area has been sectioned off by a line with four sub-micron Josephson tunnel junctions. Two thirds of the loop forms a SQUID with two larger area junctions. The area of each of its large junctions is 0.4 ($\mu $m)$^{2}$ with a desired critical current of 1-10 $\mu $A. Three of the other four sub-micron junctions have an area of 0.056 ($\mu $m)$^{2}$, where as the fourth junction has an area of 0.028 ($\mu $m)$^{2}$. Device fabrication on an insulating substrate (sapphire) requires some unconventional electron-beam lithography fabrication techniques. We will discuss the design, the fabrication process and our progress towards measuring the properties of the device at millikelvin temperatures. [Preview Abstract] |
Sunday, February 14, 2010 4:42PM - 4:54PM |
K11.00007: ABSTRACT WITHDRAWN |
Sunday, February 14, 2010 4:54PM - 5:06PM |
K11.00008: Study of Superconducting Magnesium Diboride at milli-Kelvin Temperatures J.T. Mlack, J.G. Lambert, Z.E. Thrailkill, S.A. Carabello, P.T. Galwaduge, R.C. Ramos The superconducting properties of magnesium diboride (MgB$_{2})$ were first discovered in 2001 and since then many studies of this interesting material have been performed. MgB$_{2}$ has a transition temperature of 40K and has been typically studied down to around 4.0K. We report results of recent current-voltage measurements, at milli-Kelvin temperatures, of MgB$_{2}$-based Josephson junctions obtained from our collaborators [1]. We investigate its I-V characteristics and the structure of its sub-gap resistance.\\[4pt] [1] Samples were obtained from Prof. Xiaoxing Xi's Research group at Temple University. [Preview Abstract] |
Sunday, February 14, 2010 5:06PM - 5:18PM |
K11.00009: Synthesis Methods for the Creation of Gold Nanoparticle Heat Transfer Fluids Erika Swartz, Rebecca Christianson, Jessica Townsend, Thomas Kodger, David Weitz In the past fifteen years, nanofluids have been studied as heat transfer and storage fluids. The citrate reduction synthesis method, originally developed in the 1950's, produces stable aqueous solutions of gold nanoparticles for this application. A variety of particle sizes can be produced by varying the citrate concentration at reduction. In this work, we present a repeatable synthesis protocol for solutions of gold nanoparticles. Our investigation of the heat transfer and storage properties of nanofluids required gold solutions with volume fractions above the upper limits reported in the literature for the citrate synthesis. We report protocols to create stable suspensions of highly concentrated gold nanofluid. In addition, we describe protocols and methods for the controlled destabilization of these fluids in order to study their properties when aggregated. [Preview Abstract] |
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