Bulletin of the American Physical Society
72nd Annual Gaseous Electronics Conference
Volume 64, Number 10
Monday–Friday, October 28–November 1 2019; College Station, Texas
Session LW2: Plasma Materials II |
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Chair: Pascal Chabert, École Polytechnique Room: Century II |
Wednesday, October 30, 2019 1:45PM - 2:00PM |
LW2.00001: Advanced Manufacturing with Atmospheric Pressure Plasmas: Electrostatic Focusing of Printed Silicon Nanocrystals Rebecca Anthony, Alexander Ho Among methods for nanocrystal (NC) synthesis, plasmas are among the most competitive for their versatility, facile operation, and high quality products. However, most processes for using these NCs in applications still require multiple steps including synthesis, collection, surface modification, deposition, and patterning. Here we present our work on combining these steps for an advanced manufacturing tool that couples the synthesis process with direct deposition into patterned layers using an RF microplasma operated at atmospheric pressure that is driven using an additive manufacturing platform. Using this method, we can create directed patterns of tunable-size silicon NCs, sidestepping the intermediate processing steps for a streamlined on-demand synthesis and deposition approach. The linewidth we can achieve is limited by gas flow and reactor geometry--unless we exploit the inherent charge carried by the NCs produced in plasmas and use electrostatic focusing to narrow the deposition. Our results indicate that applying a DC electric field to the deposition stage allows improved coherence of the NC deposition. This electrostatic focusing allows us to tighten the linewidth of our Si NC patterns across a range of sizes and conditions, with applied voltages tuned according to an assumed particle charge of \textasciitilde 3e. This points towards an increasingly competitive method for additive manufacturing of NC patterns using plasmas. [Preview Abstract] |
Wednesday, October 30, 2019 2:00PM - 2:15PM |
LW2.00002: Synthesis of few-layer graphene using microwave-exited atmospheric pressure plasma Mineo Hiramatsu, Koki Miyashita, Taishu Oyama, Keigo Takeda, Hiroki Kondo, Masaru Hori Graphene-based materials can be synthesized by several plasma enhanced chemical vapor deposition techniques. However, ion bombardment induces the defects. In this work, microwave-excited atmospheric pressure plasma [1] was applied to the synthesis of few-layer graphene on Cu substrate. The effect of ion bombardment on the growing surface can be removed due to the high-pressure operation. The microwave (2.45 GHz) propagates from the top of the deposition chamber to the 60-mm-long micro-gap electrode, and slit-shaped plasma is produced. Slit separation of micro-gap electrode is 0.2 mm. The distance between the micro-gap electrode and Cu substrate is 5 mm. Growth experiments were carried out for 30 to 300 sec on heated (\textasciitilde 700ûC) Cu substrate employing He/H2/CH4 mixture at atmospheric pressure. Raman spectrum of graphene-based film formed for 300 sec was almost identical to that of the film formed for 30 sec, indicating that the number of graphene layers did not increase in spite of the increase of formation period. Despite the localized plasma shape, graphene was formed uniformly on the whole substrate (5 cm diameter in the present case). Results indicated that the self-limiting growth of graphene could be attained on the Cu substrate by supplying long-lived hydrocarbon radicals without ion bombardment using atmospheric pressure plasma. [1] A. Matsushita, et al., Jpn. J. Appl. Phys. 43, 424 (2004). [Preview Abstract] |
Wednesday, October 30, 2019 2:15PM - 2:45PM |
LW2.00003: High-rate deposition of high-density amorphous carbon films using a high-pressure plasma chemical vapor deposition Invited Speaker: Kazunori Koga Because of its mechanical strength, good wear resistance, high corrosion resistance and chemical inertness, high-density hydrogenated amorphous carbon (a-C:H) has garnered interest as a material for biotechnology, tribology, and protective coating technology. Here we aimed to establish a high density and high rate a-C:H deposition method using a parallel plate rf discharge plasma which is a promising method for large area deposition comparing with the conventional sputtering plasmas and arc plasmas. We succeeded in depositing a-C:H films at 36 nm/s for 7 Torr using Ar$+$CH$_{\mathrm{4}}$(5{\%}) discharges. The discharge region shrunk toward the discharge electrode for the higher gas pressure, while the maximum emission intensity increases, leading to a large flux of deposition precursors close to the powered electrode. We also succeeded in depositing the a-C:H of 1.8 g/cc at 81 nm/min using Ar$+$H$_{\mathrm{2}}+$C$_{\mathrm{6}}$H$_{\mathrm{8}}$ plasmas with a substrate bias at 5 Torr. Effects of heavy hydrocarbon radicals, hydrogen atoms and energetic ions have been discussed. [Preview Abstract] |
Wednesday, October 30, 2019 2:45PM - 3:00PM |
LW2.00004: Reactor Scale Modeling of Nanoparticle Growth in Low Temperature Plasmas Jordyn Polito, Steven Lanham, Himashi Andaraarachchi, Zhaohan Li, Zichang Xiong, Uwe Kortshagen, Mark J. Kushner Low temperature dusty plasmas are an alternative to gas-thermal and liquid phase technologies for nanoparticle synthesis. Nanoparticles grown in plasmas have a wide variety of controllable properties that can be tuned by changing plasma parameters. Understanding synergistic effects of nanoparticle growth in plasmas could aid in rapid development of new materials. Modeling these systems has been challenged by the complexity and computational expense of particle-based or sectional-based approaches. In this work we describe a fluid-based computational approach to investigation of plasma based nanoparticle growth. The Hybrid Plasma Equipment Model (HPEM), a 2D reactor scale simulator, was adapted to enable reactions having growing particles. Modifications to the model self-consistently track particle mass and diameter evolution. The demonstration system examines Si nanoparticle growth in an argon inductively-coupled-plasma sustained in a flow tube (pressure tens to hundreds mTorr, diameter \textless 1 cm) in which SiH$_{\mathrm{4}}$ is injected [1]. Results for trends in silicon nanoparticle particle growth as a function of operating parameters such as gas flow rate and power deposition will be discussed. [1] U. Kortshagen et al. Chem. Rev. 116, 11061 (2016). [Preview Abstract] |
Wednesday, October 30, 2019 3:00PM - 3:15PM |
LW2.00005: Study of an optical emission in the laser ablation plume of boron-rich target Shurik Yatom, Alexander Khrabryi, Igor Kaganovich, Yevgeny Raitses The work presented here studies the laser ablation of B and BN targets in vacuum and nitrogen atmosphere. The investigation of excited species present in the ablation plume and the characterization of plasma parameters is done by means of spatiotemporally resolved optical emission spectroscopy. The results show formation of BN and B2N molecules from the feedstock supplied by ablation of the target in the vacuum case and from the surrounding gas in the case of boron target in nitrogen. The domination of B2N molecular species validates the simulation results reported in Ref.1 and positions the B2N molecules as important part of BN nanotube synthesis. [Preview Abstract] |
Wednesday, October 30, 2019 3:15PM - 3:30PM |
LW2.00006: Enhancement of piezoelectric properties of nanofibers and nanocomposite membranes through corona treatment Mujibur Khan, Papia Sultana, Mohammadsadegh Saadatzi, Malik Tahiyat, Tanvir Farouk, Sourav Banerjee Nanofiber (NF) membranes of Poly (vinylidene fluoride) (PVDF), multi-wall carbon nanotube (MWCNTs) reinforced PVDF and Polyacrylonitrle (PAN) were treated by a direct current driven corona discharge at 6 kV and 1mA at a distance of 1 cm. The membranes were corona treated (1.5 hours) heat treated at 100$^{\mathrm{0}}$C (1 hour), and to corona and heat combined. The corona discharge was from the sample. The samples were characterized using scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and Raman spectroscopy. The FTIR of the untreated PVDF NFs showed a peak signal at 796cm$^{\mathrm{-1}}$ ($\alpha $-phase), which was absent in the treated samples. The Raman spectroscopy of the corona treated PVDF NFs showed a distinct shift from 873cm$^{\mathrm{-1}}$ to 877cm$^{\mathrm{-1}}$ ($\beta $-phase). Electro Paramagnetic Resonance (EPR) showed the intensity of free radicals increases by 8{\%} with corona treatment. Drop ball tests were performed to measure the piezoelectric response of the NF membranes. The piezoelectric coefficient (d$_{\mathrm{33}})$ of the pristine PVDF NFs was increased from 0 to 102 pC/N due to the heat and corona treatment., The increase was from 0 to 52 pC/N for MWCNT reinforced PVDF NFs. PVDF samples showed the highest d$_{\mathrm{33}}$, while the MWCNT reinforced PVDF showed the maximum capacitance (0.93 nF). [Preview Abstract] |
Wednesday, October 30, 2019 3:30PM - 3:45PM |
LW2.00007: The Influence of the Magnetic Field on the Deposition Rate and Ionized Flux Fraction in the HiPIMS Discharge Jon T. Gudmundsson, Hamidreza Hajihoseini, Martin Cada, Zdenek Hubiccka, Selen Unaldi, Michael A. Raadu, Nils Brenning, Daniel Lundin The effect of the magnetic field strength $|{\bf B}|$ and geometry (degree of balancing) on the deposition rate and ionized flux fraction $F_{\rm flux}$ in dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) when depositing titanium are explored [1]. The magnetic field only influences the dcMS deposition rate slightly. The deposition rate during HiPIMS operated with fixed voltage increases from 30\% to 90\% of the dcMS deposition rate as $|{\bf B}|$ is decreased but $F_{\rm flux}$ decreases. In contrast, when operating the HiPIMS discharge in fixed peak current mode both the deposition rate and $F_{\rm flux}$ increase with decreasing $|{\bf B}|$. The measured quantities, the deposition rate and ionized flux fraction, are then related to the ionization probability $\alpha_{\ŗm t}$ and the back attraction probability of the sputtered species $\beta_{\rm t}$. We show that the fraction of the ions of the sputtered material that escape back attraction increases by 30\% when $|{\bf B}|$ is reduced during operation in fixed peak current mode while the ionization probability of the sputtered species increases with increased discharge current when operating in fixed voltage mode. [1] Hajihoseini et al. {\em Plasma} {\bf 2} (2019) 201 [Preview Abstract] |
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