Bulletin of the American Physical Society
63rd Annual Gaseous Electronics Conference and 7th International Conference on Reactive Plasmas
Volume 55, Number 7
Monday–Friday, October 4–8, 2010; Paris, France
Session TF2: Plasma Nanotechnologies and Flexible Electronics II |
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Chair: Tomohiro Nozaki, Tokyo Institute of Technology, Japan Room: Petit Amphitheatre |
Friday, October 8, 2010 10:30AM - 10:45AM |
TF2.00001: Plasma produced nanocrystals for efficient nanocrystal light emitting devices Rebecca Anthony, Kai-Yuan Cheng, Russel Holmes, Uwe Kortshagen Low temperature plasmas are a unique source for the synthesis of silicon nanocrystals. While silicon in its bulk form is a poor optical emitter, rather efficient emission has been demonstrated with plasma produced nanocrystals. Quantum yields for photoluminescence exceeding 60{\%} can be achieved with proper surface functionalization of the silicon nanocrystals. In this presentation, we point out that the surface coverage with hydrogen plays a crucial role for the photoluminescence quantum yield. Hydrogen coverage is a direct consequence of the plasma synthesis, since nanocrystals are exposed to a constant flux of atomic hydrogen during their growth in the plasma. While efficient photoluminescence of silicon nanocrystals has been demonstrated in the past, achieving efficient electrically pumped luminescence has been a challenge. In this work, we have incorporated plasma-produced silicon nanocrystals into a hybrid organic-silicon nanocrystals light emitting device. Through optimization of the device structure, we have been able, for the first time, to achieve electrically pumped luminescence that approaches the intrinsic limit of the device structure, at which the external quantum efficiency is only limited by the photoluminescence quantum yield of the nanocrystals and the photon outcoupling efficiency. [Preview Abstract] |
Friday, October 8, 2010 10:45AM - 11:00AM |
TF2.00002: Silicon nanocrystals surface engineering by low-pressure plasmas and atmospheric-pressure microplasmas Davide Mariotti, Vladimir Svrcek, Ashish Mathur, Michio Kondo Quantum confined silicon nanocrystals (SiNCs) may offer great opportunities in a wide range of applications due to several favorable characteristics. Firstly, silicon has limited environmental concerns, is considered a safe element and can rely on a well-established industrial know-how. Furthermore, silicon at the nanoscale is revealing interesting and useful properties. The potential applications include photovoltaics, optoelectronics and health care technology. However the control and synthesis of desired SiNCs surface characteristics are crucial for successful device integration and are currently fueling the debate on achieving accurate measurements of SiNCs properties. We have therefore investigated the possibility of using carbon as the main element to provide desired surface functionalization and/or passivation. In the first case we have used SiNCs to catalyze the growth of carbon nanotubes in microwave low-pressure methane plasma. A second different approach has been to use atmospheric-pressure microplasma to provide C-terminations to SiNCs in ethanol dispersion. [Preview Abstract] |
Friday, October 8, 2010 11:00AM - 11:15AM |
TF2.00003: Crystallographic analyses of carbon nanowalls using synchrotron X-ray Hiroki Kondo, Wakana Takeuchi, Makoto Sekine, Masaru Hori, Mineo Hiramatsu, Ichiro Hirosawa, Osami Sakata, Shigeru Sakata Carbon nanowalls (CNWs) consist of stacked graphene sheets vertically-standing on substrates. In addition to high aspect ratio and large specific surface area, the CNWs are expected to have high carrier mobility and current carrying capability as well as the graphene sheets. Therefore, they are promising candidates as channel and electrode materials for the future functional devices. However, crystalline structures of CNWs have not been sufficiently clarified yet. In this study, we investigated the crystalline structures of CNWs using synchrotron X-ray. According to synchrotron X-ray diffraction (SR-XRD), it is confirmed that, with decreasing disorder components in graphene sheets, interlayer spacing between the stacked graphene sheets in the CNWs becomes closer to that of bulk graphite. On the other hand, grazing incidence X-ray scattering (GIXS) measurement results indicate 1.2-1.6 nm-sized scattering substance in the CNWs. These results suggest hierarchical nano-domain structures in the CNWs. Furthermore, theses experimental results suggest that the SR-XRD is useful to evaluate crystalline and domain structures of carbon nanomaterials such as the CNWs. [Preview Abstract] |
Friday, October 8, 2010 11:15AM - 11:30AM |
TF2.00004: Structure Control and Etching Stabilities of Carbon Nanowalls Grown by Low Magnetic-Field Helicon Plasma CVD Masahiro Yamazaki, Toshiaki Kato, Ryo Ueda, Toshiro Kaneko, Rikizo Hatakeyama, Chiharu Takahashi The structure controlled carbon nanowalls (CNWs) are grown by low magnetic-field helicon plasma CVD [1, 2]. It is found that the wall distance and wall height of CNWs can be independently controlled by adjusting the ion energy coming to a deposition substrate during their growth. The etching stabilities of such high quality CNWs are also investigated through the electron cyclotron resonance (ECR) plasma etching. By carefully controlling the mixture gas condition of ECR plasma etching, amorphous carbon between the substrate and CNWs are selectively etched out. Furthermore, when we perform the SiO2 etching for such an amorphous-carbon removed CWNs/SiO2/Si sample, the nanowall like structures are found to be formed on the layer of SiO2. This nanowall like SiO2 structure can be useful for the wide range of optical and electrical applications. [1] G. Sato, W. Oohara, and R. Hatakeyama: Appl. Phys. Lett. 85 (2004) 4007. [2] G. Sato, T. Morio, T. Kato, and R. Hatakeyama: Jpn. J. Appl. Phys. 45 (2006) 5210. [Preview Abstract] |
Friday, October 8, 2010 11:30AM - 11:45AM |
TF2.00005: Controlled Introduction of Nitrogen Species to Improve Nano-functionality Xiujuan (Jane) Dai, Ying Chen, Tao Tao, Zhiqiang Chen, Luhua Li, Peter Lamb, Bronwyn Fox, Xungai Wang The incorporation of nitrogen (N) species into nanomaterials has played an important role in biomedicine, solar energy, environmental cleaning, optical and electrical devices etc. N-doping of semiconductor oxides (e.g. TiO$_{2})$ has been shown to increase photocatalytic activity and reduce band gaps. Incorporation of N into CNTs has been shown to enhance conductivity and surface chemical activity. However, controlled introduction of a sufficient density of the desired N-species and determination of the mechanisms are still major challenges. A novel combined plasma mode has been developed that allows control of the required N-species or N-functional group and its incorporation into a range of nanomaterials (TiO$_{2}$, SnO$_{2}$, CNTs, BNNTs etc.). The N-containing precursor is selected and the process parameters are designed for the specific application (solar cell, biosensor, nanocomposite etc.). Ion bombardment and UV radiation from continuous wave plasma provides surface etching to produce bond scission or introduce free radicals on the substrate. Pulsed plasma introduces the required N-species onto the sites without disturbance from charged particles and UV radiation. The detailed N chemical states in the selected nanomaterials have been studied by XPS to help understand their chemical nature and effects on the improvement of visible-light response, conductivity and surface chemical activity. [Preview Abstract] |
Friday, October 8, 2010 11:45AM - 12:00PM |
TF2.00006: Investigation of Plasma Interactions with Soft Materials via Combinatorial Plasma-Process Analyzer for Plasma Nano Processes Yuichi Setsuhara, Ken Cho, Kosuke Takenaka, Masaharu Shiratani, Makoto Sekine, Masaru Hori Materials systems with inorganic/soft materials hybrid structures are of great importance for development of nano devices including next-generation ULSIs, NEMS and bio-chips; e.g., photoresist for EUV lithography, low-k materials and functional organic materials for flexible electronics. For successful development of these advanced device technologies, it is of great significance to establish scientific basis of understanding plasma interactions with soft materials in terms of chemical and physical properties, however, it is greatly anticipated that optimal process conditions can be attained at a pinpoint window due to requirement of nanometer-size precision. In order to effectively carry out systematic investigations of plasma nano processes, a plasma process analyzer has been developed via combinatorial methods, in which process examinations with a continuous variation of plasma-process conditions (ion flux, radical flux) can be carried out via a continuously graded distribution of process parameters. In this presentation, design issues and performance of the combinatorial plasma-process analyzer will be presented together with results obtained for plasma-polymer interactions in terms of chemical bonding states, surface morphologies and etching characteristics. [Preview Abstract] |
Friday, October 8, 2010 12:00PM - 12:15PM |
TF2.00007: DNA-Associated Synthesis of Gold Nanoparticles by Gas-Liquid Interfacial Pulse Discharge Plasma Qiang Chen, Toshiro Kaneko, Rikizo Hatakeyama A gas-liquid interfacial discharge plasma is used for the DNA-associated synthesis of water-soluble gold nanoparticles (AuNPs) by reducing gold (III) from aqueous chloroauric acid trihydrate. The plasma is generated by a pulse power source, which can avoid the instability of DC discharges at high pressures. The high discharge current ($\sim $ampere) offers a basis for the high rate synthesis of AuNPs. Single-stranded DNA is used as the stabilizing agent since DNA molecules can be bound to the gold surface. A red shift of surface plasmon resonance (SPR) absorption of AuNPs is observed when the DNA-stabilized AuNPs are mixed with a solution including complementary DNA, which means there is aggregation of AuNPs due to the hybridization of DNA. We also synthesize AuNPs associated with various kinds of DNA such as 30-base guanine G$_{30}$, adenine A$_{30}$, cytosine C$_{30}$, and thymine T$_{30}$. It is found by comparing the intensities of SPR peaks of AuNPs after extracting them from as-synthesized samples by centrifugation that G$_{30}$ and A$_{30}$ DNA have stronger stabilizing ability for AuNPs than that of T$_{30}$ and C$_{30}$ DNA. [Preview Abstract] |
Friday, October 8, 2010 12:15PM - 12:30PM |
TF2.00008: Using Atmospheric Pressure Plasma Technology For One Step Enzyme Immobilization Arne Van Hoeck, Sabine Paulussen The immobilization of biomolecules is of great interest for a variety of applications like for e.g. biosensors, biocatalysis, lab on chips. While some methodologies are readily applicable in industrial processes, a simple and fast single step immobilization protocol would offer a cost effective alternative for straightforward production. Plasma coating technology has been recognized as an attractive technology for surface treatment of materials since it is considered as inexpensive, easy to operate and allow to reduce solvent use substantially. The most remarkable feature of non-equilibrium atmospheric pressure plasmas is the low temperature which leads to a high preservation of polymer functional groups and a minimum damage to native biomolecule structures. This work aims at the development of a new, direct immobilization strategy for biomolecules. By feeding the DBD atmospheric plasma discharge zone simultaneously with an polymer precursor and an enzyme (glucose oxidase) solution, it is possible to fabricate a bio-functional layer where the enzymes become entrapped into the polymer matrix. It will be shown that a single step technology has been developed that enables fast immobilization of biomolecules while retaining their bioactivity. The immobilized biomolecules are homogeneously distributed within the polymer coating. [Preview Abstract] |
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