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SWCNT growth on Al/Fe/Mo investigated by <i>in situ</i> mass spectroscopy
Kim, S-M,Zhang, Y,Teo, K B K,Bell, M S,Gangloff, L,Wang, X,Milne, W I,Wu, J,Jiao, J,Lee, S-B IOP Pub 2007 Nanotechnology Vol.18 No.18
<P>The effect of temperature on the growth of single-walled carbon nanotubes (SWCNTs) was investigated over the range of 725–900 °C. A cold-wall reactor consisting of a heated stage (on which the substrate for SWCNT growth (Al/Fe/Mo) was placed) and a showerhead (from which C<SUB>2</SUB>H<SUB>2</SUB> was introduced vertically into the reactor) was used for the growth. The heating was found to play two roles: (1) it generated complex hydrocarbon radicals during the growth process, as well as (2) promoting catalytic nanoparticles on the substrate during the annealing process. The optimum temperature for the highest SWCNT yield was found to be ∼860 °C. For the first time, <I>in situ</I> mass spectroscopy was used to identify the growth precursors generated from thermal pyrolysis of C<SUB>2</SUB>H<SUB>2</SUB> within this temperature range. The peak of the radicals found (C<SUB>6</SUB>H<SUB>9</SUB>, C<SUB>5</SUB>H<SUB>9</SUB> and C<SUB>6</SUB>H<SUB>13</SUB>) and the highest catalyst support particle density (Fe catalyst supported on Al<SUB><I>x</I></SUB>O<SUB><I>y</I></SUB>) was correlated to the maximum yield of single walled carbon nanotubes at the optimum growth temperature of ∼860 °C. Bottom gate SWCNT-FETs (single-walled carbon nanotube based field effect transistors) were fabricated showing a high transconductance of ∼0.12 µS and on/off ratio of ∼10<SUP>5</SUP> which are both comparable to other state-of-the-art SWCNT-FET. </P>
Electron emission from arrays of carbon nanotubes/fibres
W. I. Milne,K. B. K. Teo,M. Chhowalla,G. A. J. Amaratunga,D. Pribat,P. Legagneux,G. Pirio,Vu Thien Binh,V. Semet 한국물리학회 2002 Current Applied Physics Vol.2 No.6
The overall aim of this work is to produce arrays of eld emitting microguns, based on carbon nanotubes, which can be utilised inthe manufacture of large area eld emitting displays, parallel e-beam lithography systems and electron sources for high frequency(MWCNTs) using a dc plasma technique and a Ni catalyst. We will discuss how the density of the carbon nanotube/bres can bevaried by reducing the deposition yield through nickel interaction with a diusion layer or by direct lithographic patterning of the Nicatalyst to precisely dene the position of each nanotube/bre. Details of the eld emission behaviour of the dierent arrays ofMWCNTS will also be presented.. 2002 Published by Elsevier Science B.V.
Aligned carbon nanotubes/fibers for applications in vacuum microwave devices
W.I.Milne,K.B.K.Teo,G.A.J.Amaratunga,R.Lacerda,P.Legagneux,G.Pirio,V.Semet,V.Thien Binh 한국물리학회 2004 Current Applied Physics Vol.4 No.5
Carbon nanotubes exhibit extraordinary eld emission properties because of their high electrical conductivity, ideal high aspectratio whisker-like shape for geometrical eld enhancement, and remarkable thermal stability. This paper will describe the PECVDgrowth of vertically aligned arrays of carbon nanotubes which are suitable for use as the electron emitters in a novel type ofmicrowave amplier capable of producing of order 10 W at 30 GHz.
I.Y.Y. Bu,A.J. Flewitt,W.I.Milne 한국물리학회 2011 Current Applied Physics Vol.11 No.2
A novel layer-by-layer growth technique has been developed for the early stages of nanocrystalline silicon (nc-Si) deposition to produce an insulating incubation layer. An electron cyclotron resonance reactor is used to deposit a thin film of nc-Si by plasma enhanced chemical vapour deposition. The deposited layer is then exposed, in situ, to a dense plasma of nitrogen and hydrogen which converts defective, amorphous material into silicon nitride whilst preserving nucleating nano-crystals. This twostage process of deposition and nitrogenation is repeated four times before a thick nc-Si layer is grown on top. By converting the incubation layer into an insulator, when this material is employed as the channel layer in bottom gate thin film transistors, the accumulation layer is forced to form in a region of greater crystallinity, and devices with an electron field effect mobility of 3 cm^2 V^-1 s^-1 have been produced. These are the first bottom gate thin film transistors using a nc-Si channel with a higher field effect mobility than found in hydrogenated amorphous silicon devices.
Nitrogenation of highly sp2 bonded amorphous carbon
Sunglyul Maeng,A Tagliaferro,John Robertson,W. I. Milne,Soonil Lee 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
Amorphous carbon with a high sp2 bonding content is considered to be a poor electronic material due to its very narrow band gap and its excessive density of defect states in the gap, both of which pin the Fermi level. This paper describes the ability of nitrogen to improve the semiconducting properties of highly sp2 bonded ( 80 90 % sp2) amorphous carbon. The electron spin resonance shows a reduction in the density of gap states in nitrogenated amorphous carbon (a-C : N) with increasing nitrogen content. Photo-thermal deflection spectroscopy and ultraviolet-visual spectroscopy measurements show that the opening of the gap and clearing of the gap states occur through nitrogen incorporation into the amorphous carbon film.
DIRECT GROWTH OF MULTI-WALLED CARBON NANOTUBES ON SHARP TIPS FOR ELECTRON MICROSCOPY
M. MANN,K. B. K. TEO,W. I. MILNE,T. TESSNER 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.1
The favorable electron optical properties of carbon nanotubes (CNTs) have been studied in detail, but the application to electron sources has been limited by the complexity of the fabrication process. We report the use of Plasma Enhanced Chemical Vapor Deposition (PECVD) for the direct deposition of multi-walled CNTs onto the apex of sharply etched tungsten tips, aligned to the vertical axis of the tips. We show that these emitters have excellent stability.
Properties of a-C:H films deposited from a methane electron cyclotron wave resonant plasma
N.A.Morrison,C.William,B.Racine,W.I.Milne,E.Martinez,J.Esteve,J.L.Andujar 한국물리학회 2003 Current Applied Physics Vol.3 No.5
An electron cyclotron wave resonant methane plasma discharge was used for the high rate deposition of hydrogenated amorphous carbon (a-C:H). Deposition rates of up to 400 AA/min were obtained over substrates up to 2.5 in. in diameter with a film thickness uniformity of 10%. The deposited films were characterised in terms of their mass density, sp3 and hydrogen contents, C–H bonding, intrinsic stress, scratch resistance and friction properties. The deposited films possessed an average sp3 content, mass density and refractive index of 58%, 1.76 g/cm3 and 2.035 respectively. Mechanical characterisation indicated that the films possessed very low steady-state coefficients of friction (ca. 0.06) and a moderate shear strength of 141 MPa. Nano-indentation measurements also indicated a hardness and elastic modulus of 16.1 and 160 GPa respectively. The critical loads required to induce coating failure were also observed to increase with ion energy as a consequence of the increase in degree of ion mixing at the interface. Furthermore, coating failure under scratch test conditions was observed to take place via fracture within the silicon substrate itself, rather than either in the coating or at the film/substrate interface. 2003 Elsevier B.V. All rights reserved.
Achievements and lessons learned from the operation of KSTAR plasma control system upgrade
Hahn, Sang-hee,Penaflor, B.G.,Milne, P.G.,Bak, J.G.,Eidietis, N.W.,Han, H.,Hong, J.S.,Jeon, Y.M.,Johnson, R.D.,Kim, H.-S.,Kim, HeungSu,Kim, Y.J.,Kwon, G.I.,Lee, W.R.,Woo, M.H.,Sammuli, B.S.,Walker, M. Elsevier 2018 Fusion engineering and design Vol.130 No.-
<P><B>Abstract</B></P> <P>Results on the integration and the operation of the KSTAR plasma control system (PCS) upgrade are given. Real-time hardware, new realtime-capable operating system, and a brand-new data acquisition are assembled in order to extend the performance and compatibility with modern computer systems. The first full commissioning and eventual routine use performed in 2016 so that the system can now acquire more than 400 channels for more than 100 seconds of data with 5 kHz sampling. The performance test results are summarized, featuring In/Out streaming echo tests and the synchronization verifications. Examples of general performance improvements are demonstrated, and additional features added to the software are also described.</P>
Field emission properties of self-assembled silicon nanostructures formed by electron beam annealing
S. Johnson,A. Markwitz,M. Rudolphi,H. Baumann,S.P. Oei,K.B.K. Teo,W.I. Milne 한국물리학회 2006 Current Applied Physics Vol.6 No.3
Arrays of silicon nanostructures on n- and p-type silicon (100) substrates were fabricated using electron beam annealing of untreated silicon at 1100 C. Following annealing for 15 s, the nanostructures exhibit an average height of 8 ± 1 nm and a surface density of 11 lm2, independent of the substrate conduction type. Following annealing for 600 s the individual nanostructures coalesce and the surface appears roughened with an rms roughness of 30 nm. The field emission properties of these nanostructure arrays have been assessed and electron emission through Fowler–Nordheim tunnelling was confirmed. The difference in threshold field for electron emission from the nanostructured and roughened substrates is related to the geometrical differences between the substrate surfaces. At large electric fields, space charge limited conduction dominates the field emission characteristics of the nanostructured surface.