Bulletin of the American Physical Society
64th Annual Gaseous Electronics Conference
Volume 56, Number 15
Monday–Friday, November 14–18, 2011; Salt Lake City, Utah
Session ET4: Plasmas and Nanotechnology |
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Chair: Masaru Hori, Nagoya University Room: 255A |
Tuesday, November 15, 2011 2:00PM - 2:30PM |
ET4.00001: The physics and applications of nanomaterials produced with nonthermal plasmas Invited Speaker: Nonthermal plasmas provide an intriguing environment for the synthesis of nanomaterials. Not only does the unipolar negative charging of nanoparticles in plasmas yield significantly more monodisperse particle size distributions than other gas phase processes; the selective heating of small particulates in plasmas also enables producing high quality nanocrystals of high melting point materials. Nonthermal plasma hence proof to be ideal media for the synthesis of nanocrystals of covalently bonded semiconductors of the group IV and group III-V materials systems. This talk will discuss the unique physical principles of nanoparticle synthesis in plasmas. The presentation will also give examples of the applications of such plasma-produced nanomaterials to photovoltaic and light-emitting devices. The presenter hopes to make the case that nonthermal plasmas can fill a unique niche in the synthesis of nanomaterials that may proof of significant nonthermal value for applications in materials engineering, printed electronics, and renewable energy technology. [Preview Abstract] |
Tuesday, November 15, 2011 2:30PM - 2:45PM |
ET4.00002: Comparison of Upright Carbon Nanotwists Treated by Plasma with Different Types of Gases Yoshiyuki Suda, Yuki Sugioka, Hirofumi Takikawa, Hideto Tanoue, Hitoshi Ue, Kazuki Shimizu, Yoshito Umeda Carbon nanotwist (CNTw) is a kind of helical carbon nanofiber and a good candidate for field emission material as well as carbon nanotube. We have used CNTws as a base material of field emitter (FE). CNTws were synthesized by catalytic chemical vapor deposition [1]. The CNTw paste was prepared by mixing CNTw with an organic binder. The CNTw FE was fabricated by screen-printing the paste on substrates. Then, the FE surface was treated with plasma. A quartz plate was glued on both electrode surfaces of the plasma reactor. A glow discharge was generated uniformly in He gas, and dielectric barrier discharge (DBD) was generated in N$_{2}$ gas. Three effects on the CNTw dots by DBD are shown as follows: (i) making CNTws stand up, (ii) relocation of CNTws, and (iii) etching of CNTws. By contrast, the three effects were not obtained by glow discharge. Luminescence from phosphor on the anode of the CNTw FE treated by DBD for 30 s was uniform. FE characteristics were improved by an increase of upright CNTws [2].\\[4pt] [1] Y. Hosokawa, et al, \textit{Res. Lett. Mater. Sci.}, \textbf{2007}, 59167, 2007\\[0pt] [2] Y. Hosokawa, et al, \textit{J. Phys. D: Appl. Phys.}, \textbf{41}, 205418, 2008 [Preview Abstract] |
Tuesday, November 15, 2011 2:45PM - 3:00PM |
ET4.00003: Spatiotemporal evolution of light scattering from growing nanoparticles in an RF argon-silane plasma Steven Girshick, Pulkit Agarwal, Johannes Berndt, Eva Kovacevic, Laifa Boufendi Measurements were made of the spatial and temporal profiles of laser light scattering from silicon nanoparticles that nucleate and grow in a capacitively-coupled RF argon-silane plasma. The measurements are compared to simulation results of a 1-D plasma-aerosol numerical model. The plasma was operated at 13.56 MHz with a 4-cm electrode gap. Experiments and simulations were conducted for various pressures (in the 100-mTorr range), RF voltages and flow rates of argon and silane. A plasma fluid model is self-consistently coupled to a sectional aerosol model which considers particle nucleation and surface growth, coagulation, particle charging, and particle transport by neutral gas drag, ion drag, electrostatic forces and gravity. We discuss effects of system operating parameters, and areas of agreement as well as discrepancies between the numerical model and the experimental measurements. [Preview Abstract] |
Tuesday, November 15, 2011 3:00PM - 3:15PM |
ET4.00004: Control of transport and distribution of dust particles via Electrical Asymmetry Effect Shinya Iwashita, Giichiro Uchida, Julian Schulze, Edmund Schuengel, Peter Hartmann, Masaharu Shiratani, Zoltan Donko, Uwe Czarnetzki We are developing a novel method to manipulate particles in capacitively coupled rf discharges via the Electrical Asymmetry Effect, which allows to control both the spatial potential profile as well as the ion density distribution by adjusting the phase angle $\theta $ between a fundamental frequency and its second harmonic. We report first experimental results of this method using SiO$_{2}$ particles of around 1 $\mu $m in size, which are inserted into an argon discharge operated at low pressures. By changing $\theta $ from 0 to 90 degree particles are transported rapidly from the plasma-sheath region around the lower powered electrode to that around the upper grounded electrode. The spatial distribution of forces exerted on particles, such as ion drag and electrostatic forces, will be discussed based on PIC simulation results. Funding: German Federal Ministry for the Environment (0325210B), Alexander von Humboldt Foundation, RUB Research Department Plasma, Hungarian Scientific Research Fund (OTKA-K-77653+IN-85261) [Preview Abstract] |
Tuesday, November 15, 2011 3:15PM - 3:30PM |
ET4.00005: Two dimensional fluid simulation in capacitively coupled silane discharges Yuan-Hong Song, Xiang-Mei Liu, Yan Wang, You-Nian Wang A two-dimensional (2D) self-consistent fluid model is developed to describe the formation, subsequent growth, transport and charging mechanisms of nanoparticles in a capacitively coupled silane plasma. In this discharge process, large anions are produced by a series of chemical reactions of anions with silane molecules, while the lower limit of the initial nanoparticles are taken as large anions to directly link the coagulation module with the nucleation module. The influences of source parameters on the electron density, electron temperature, nanoparticle uniformity, and deposition rate, are carefully studied. Moreover, the behavior of silicon plasma mixed with SiH$_{4}$, N$_{2}$ and O$_{2}$ in a pulse modulated capacitively coupled plasma has been also investigated. Results showed a strong dependence of the electron density and electron temperature on the duty cycle and the modulated frequency. [Preview Abstract] |
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