Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session Z28: Nanotechnology II |
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Sponsoring Units: FIAP Chair: Keith Williams, University of Virginia, Room: 330 |
Friday, March 20, 2009 11:15AM - 11:27AM |
Z28.00001: Fundamental Etching and Roughening Mechanisms of Photoresist Polymers during Plasma Processing Dustin Nest, Ting-Ying Chung, David Graves, Florian Weilnboeck, Robert Bruce, Tsung Cheng Lin, Ray Phaneuf, Gottlieb Oehrlein, Eric Hudson, Deyan Wang, Cecily Andes Reducing the etching and roughening of photoresist polymers during plasma processing is required as optical lithography for integrated circuit manufacture is extended to patterning features with critical dimension control on the order of nanometers. We use a vacuum beam system to simulate plasma exposure but under well-defined conditions. Samples are exposed to well-characterized beams of ions, vacuum ultraviolet (VUV) radiation, and electrons under high vacuum conditions. Post-exposure analysis includes atomic force and scanning electron microscopy and FTIR spectroscopy. We show that VUV radiation, ion bombardment, the ion / photon flux ratio and heating all play a role in the roughening of current-generation PMMA-based 193 nm photoresists. VUV radiation breaks carbon-oxygen bonds to a depth of approximately 100 nm whereas ion bombardment forms a dehydrogenated surface layer. Qualitatively similar roughening was observed in plasmas with the same ion bombardment energy and ion and VUV fluence. [Preview Abstract] |
Friday, March 20, 2009 11:27AM - 11:39AM |
Z28.00002: Understanding the Differences between Electron and Ion Guiding Susanta Das, Buddhika S. Dassanayake, John A. Tanis, Nikolaus Stolterfoht Significant differences in the transmission and guiding of slow positive ions and fast electrons through insulating PET nanocapillary foils have been observed.$^{1,2}$ While ions are transmitted without energy loss or change in charge state even when the foil is tilted with respect to the incoming ion beam, electrons undergo inelastic as well as elastic scattering leading to considerable reduction in the transmitted intensities. The underlying reasons for the differences between ions and electrons will be discussed and quantitative comparisons made. Qualitatively, slow positive ions are fully neutralized when striking a surface and consequently deposit all of their charge, whereas electrons can be elastically or inelastically scattered.$^{3}$ Additionally, secondary electron emission by incident ions increases the deposited charge, while this same emission decreases the deposited charge for electrons. *Supported by Research Corporation $^{1}$N. Stolterfoht \textit{et al}., Phys. Rev. A \textbf{77}, 032905 (2008). $^{2}$S. Das \textit{et al}., Phys. Rev. A \textbf{76}, 042716 (2007). $^{3}$B. Stix \textit{et al}., XXV ICPEAC, Freiburg, Germany, July 2007, Abstracts, MO 128. [Preview Abstract] |
Friday, March 20, 2009 11:39AM - 11:51AM |
Z28.00003: Laser Manipulation of Nanostructures Dinko Chakarov This work describes a new method for controlling the pattern into which nanoparticles in a disordered metal-nanoparticle layer organize themselves by a single light pulse. [1]. The phenomena behind formation of one- and two-dimensional grating patterns are attributed to interference effects between the incident light and waveguided modes. Such self-patterning behavior could be useful for the fabrication of complex nanostructures and advanced photonic devices. \\[3pt] [1]. L. Eurenius, C. H\"{a}gglund, E. Olsson, B. Kasemo and D. Chakarov, ``Grating formation by metal nanoparticle-mediated coupling of light into waveguided modes,'' \textit{Nature Photon. }\textbf{2, }360 (2008). [Preview Abstract] |
Friday, March 20, 2009 11:51AM - 12:03PM |
Z28.00004: A new method of nano-manipulation with AFM derived from nanotribology Suenne Kim, Daniel Ratchford, Xiaoqin Li Based on principles of nanotribology, a new approach is explored for manipulating nanoparticles (ranging from 5nm to 60nm in diameter) with an Atomic Force Microscope (AFM). In this new approach, one first kicks a nanoparticle. Immediately following the kicking event, static friction is greatly reduced. One can then dribble the nanoparticle to the desired position in the tapping (imaging) mode of the AFM. The major advantage of this scheme lies in the active manipulation with simultaneous visual feedback. Our study revealed the mechanism for the nano-displacement is primarily governed by the ``stick'' events of the stick-slip process. We also found that the manipulation can be effectively controlled by adjusting the scanning speed, and the critical speed depends on the local roughness of the surface. [Preview Abstract] |
Friday, March 20, 2009 12:03PM - 12:15PM |
Z28.00005: Single-Particle Placement on a large scale Pradeep Bhadrachalam, Hong-Wen Huang, Vishva Ray, Seong Jin Koh The capability of positioning single nanoparticles onto exact substrate locations holds prime technological and scientific importance. We present a novel technique to precisely place exactly one single nanoparticle onto a targeted substrate location on a large scale. This was done by defining an electrostatic guiding structure using CMOS compatible fabrication technology, which guides exactly one single 20nm gold nanoparticle onto a desired substrate location with a success rate over 90\%. The measured precision of this single-particle placement (SPP) was 12.1nm. This technique has an inherent capability of limiting one single nanoparticle for each target location. Theorectical calculations has revealed that this self-limiting capability originates from an increase of free energy barrier after a nanoparticle is placed on the target location, effectively blocking the approach of other nanoparticles. We also demonstrate size-selective placement of single nanoparticles, where individual nanoparticles of different sizes are guided to different target locations on the same substrate. [Preview Abstract] |
Friday, March 20, 2009 12:15PM - 12:27PM |
Z28.00006: Magnetically Driven Swimming of Nanoscale Colloidal Assemblies Jennifer Breidenich, Jason Benkoski, Lance Baird, Ryan Deacon, H. Bruce Land, Allen Hayes, Pei Keng, Jeffrey Pyun At microscopic length scales, locomotion can only be generated through asymmetric conformation changes, such as the undulating flagellum employed by protozoa. This simple yet elegant design is optimized according to the dueling needs of miniaturization and the fluid dynamics of the low Reynolds number environment. In this study, we fabricate nanoscale colloidal assemblies that mimic the head + tail structure of flagellates. The assemblies consist of two types of magnetic colloids: 25 nm polystyrene-coated Co nanoparticles, and 250 nm polyethylene glycol coated magnetite nanoparticles. When mixed together in N-dimethylformamide, the Co nanoparticles assemble into flexible, segmented chains ranging in length from 1 - 5 $\mu$m. These chains then attach at one end to the larger magnetic beads due to magnetic attraction. This head + tail structure aligns with an external uniform magnetic field and is actuated by an oscillating transverse field. We examine the effects of Co nanoparticle concentration, magnetite bead concentration, magnetic field strength, and oscillation frequency on the formation of swimmers and the speed of locomotion. [Preview Abstract] |
Friday, March 20, 2009 12:27PM - 12:39PM |
Z28.00007: Observation of Fano Interference and Field Dependence by Raman Spectroscopy of Molecularly Doped Silicon Brian Burke, Keith Williams, Jack Chan We have investigated various doping techniques on silicon to form thin, highly p-doped layers near the surface (approximately 10 nm). We are able to observe through Raman spectroscopy the signature Fano lineshape present in the zone-centre optical phonon. We have defined high resolution channels by electron beam lithography and subsequently annealed adsorbed dopant molecules into the silicon lattice by RTA. We have performed sheet resistance measurements as well as Raman mapping to characterize the doping profile. The Raman laser line of 325 nm provides a penetration depth of roughly 8 nm, ideal for studying the surface of silicon. After studying the highly doped channel, electrodes were deposited and field dependence measurements were made. Additionally, IETS and transport measurements have been conducted for various geometries to compare with Raman data. [Preview Abstract] |
Friday, March 20, 2009 12:39PM - 12:51PM |
Z28.00008: Profiling surfaces with a carbon nanotube oscillator Adrian Popescu, Lilia Woods, Igor Bondarev A practical device for profiling surfaces is proposed, as an alternative to an Atomic Force Microscopy (AFM) tip. The device consists of a finite length double wall carbon nanotube oscillator with the outer tube being stationary and oriented perpendicular to the surface plane. By investigating the changes in the oscillatory behavior of the inner tube due to the proximity of the surface, the roughness of the surface can be determined. The role of the length and the initial extrusion of the moving tube, and the friction losses in the motion process are also explored. We suggest that such a device can be virtually a non-fatigue, non-wear system, and that it is possible to obtain a higher in-plane resolution as compared to the ``traditional'' AFM tip. [Preview Abstract] |
Friday, March 20, 2009 12:51PM - 1:03PM |
Z28.00009: An Electrodynamics Ratchet Motor Jiufu Lim, John Sader, Paul Mulvaney Brownian ratchets are often used to generate translational motion for biological separation processes and colloidal transport. This talk will propose a Brownian ratchet motor that enables the transduction of electrical energy into rotary micro-mechanical work. This is achieved through torque generation provided by boundary shaping of equipotential surfaces. Stochastic simulations elucidate the performance characteristics of this device as a function of its geometry. Miniaturization to nanoscale dimensions yields rotational speeds in excess of 1kHz, which is comparable to biomolecular motors of similar size. [Preview Abstract] |
Friday, March 20, 2009 1:03PM - 1:15PM |
Z28.00010: When a magnetized quantum wire can act as an ``active" laser medium Manvir Kushwaha We report on the theoretical investigation of magnetoplasmon excitations in a quantum wire characterized by a confining harmonic potential and in the presence of a perpendicular magnetic field. The problem involves two length scales: $l_0=\sqrt{\hbar/m^*\omega_0}$ and $l_c=\sqrt{\hbar/m^*\omega_c}$, which characterize the relative strengths in the interplay of confinement and the magnetic field. We embark on the charge-density excitations within a two-subband model in the framework of Bohm-Pines' random-phase approximation. The main focus of our study is the (intersubband) magnetoroton excitation which changes the sign of its group velocity twice before merging with the respective single-particle continuum. We analyze the terms and conditions within which the magnetoroton excitation persists in the quantum wires. It is suggested that the electronic device based on such magnetoroton modes can act as an {\it active} laser medium. [Preview Abstract] |
Friday, March 20, 2009 1:15PM - 1:27PM |
Z28.00011: Suppression of electric field domains in semiconductor superlattices with side shunting layer Huidong Xu, Andreas Amann, Eckehard Sch{\"o}ll, Stephen Teitsworth We have numerically studied the electronic transport properties of a weakly-coupled semiconductor superlattice that possesses a conductive side shunting layer, using a model that includes lateral dynamics in each quantum well of the superlattice [1]. Depending on the lateral size of the superlattice quantum wells and the quality of the connection between the shunt layer and the superlattice, the shunt may inhibit the formation of electric field domains in the superlattice under conditions of negative differential resistance (NDR). We determine conditions to achieve a stable spatially-uniform electric field distribution, an important condition for practical NDR devices such as superlattice THz oscillators. For a superlattice with small lateral extent, a high quality shunt stabilizes the uniform field configuration in the entire structure, whereas a lower quality shunt leads to current oscillations and/or static field domains. We characterize the bifurcations associated with the transitions between these different behaviors. [1] A. Amann and E. Sch{\"o}ll, Phys. Rev. B {\bf 72}, 165319 (2005). [Preview Abstract] |
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