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Dive into the research topics where A. R. Krauss is active.

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Featured researches published by A. R. Krauss.


Applied Physics Letters | 1997

Field emission from nanotube bundle emitters at low fields

Qing Hua Wang; T. D. Corrigan; Jiyan Dai; R. P. H. Chang; A. R. Krauss

The fabrication of nanotube field emitters with an onset field as low as 0.8 V/μm is described and the low-field electron emission mechanism is discussed. These emitters are made using nanotube cathode deposit with the addition of epoxy resin. The preferred orientation of nanotubes in nanotube bundles of the deposit is preserved. The nanotube tips are sharpened by exposing the nanotube bundle surface to a microwave oxygen plasma. The local-field enhancement factor is estimated to be 8000 by using the Fowler–Nordheim equation. The low onset field is attributed to the well-distributed, highly orientated sharp tips at the sample surface.


Applied Physics Letters | 2001

Synthesis and characterization of highly-conducting nitrogen-doped ultrananocrystalline diamond films

Somnath Bhattacharyya; O. Auciello; J. Birrell; John A. Carlisle; L. A. Curtiss; Amanda Goyette; Dieter M. Gruen; A. R. Krauss; J. Schlueter; Anirudha V. Sumant; Peter Zapol

Ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma-enhanced chemical-vapor-deposition method using a CH4(1%)/Ar gas mixture and 1%–20% nitrogen gas added. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 Ω−1 cm−1) with increasing nitrogen content. Conductivity and Hall measurements made as a function of film temperature down to 4.2 K indicate that these films have the highest n-type conductivity and carrier concentration demonstrated for phase-pure diamond thin films. Grain-boundary conduction is proposed to explain the remarkable transport properties of these films.


Diamond and Related Materials | 2001

Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices

A. R. Krauss; O. Auciello; D. M. Gruen; A. Jayatissa; Anirudha V. Sumant; J. Tucek; Derrick C. Mancini; Nicolaie Moldovan; A. Erdemir; D. Ersoy; Michael N. Gardos; Hans Gerd G. Busmann; E. M. Meyer; M.Q. Ding

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. A major problem with the Si-based MEMS technology is that Si has poor mechanical and tribological properties J.J. Sniegowski, in: B.


Applied Physics Letters | 1994

Fullerenes as precursors for diamond film growth without hydrogen or oxygen additions

Dieter M. Gruen; Shengzhong Liu; A. R. Krauss; J.S. Luo; Xianzheng Pan

Diamond films are predominantly grown using approximately 1% of a hydrocarbon precursor in hydrogen gas. Hydrogen is generally believed to be necessary for the diamond thin‐film growth process. However, hydrogen in varying amounts is inevitably incorporated in the growing diamond lattice, leading to structural defects. We report here the successful growth of diamond films using fullerene precursors in an argon microwave plasma, a unique development achieved without the addition of hydrogen or oxygen. We speculate that collisional fragmentation of C60 to give C2 could be responsible for the high growth rate of the very‐fine‐grained diamond films.


Applied Physics Letters | 2000

Composition-control of magnetron-sputter-deposited (BaxSr1 - X)Ti1 + yO3 + z thin films for voltage tunable devices

Jaemo Im; O. Auciello; P. K. Baumann; S. K. Streiffer; D. Y. Kaufman; A. R. Krauss

Precise control of composition and microstructure is critical for the production of (BaxSr1−x)Ti1+yO3+z (BST) dielectric thin films with the large dependence of permittivity on electric field, low losses, and high electrical breakdown fields that are required for successful integration of BST into tunable high-frequency devices. Here, we present results on composition-microstructure-electrical property relationships for polycrystalline BST films produced by magnetron-sputter deposition, that are appropriate for microwave and millimeter-wave applications such as varactors and frequency triplers. Films with controlled compositions were grown from a stoichiometric Ba0.5Sr0.5TiO3 target by control of the background processing gas pressure. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O2) process pressure, while the O2/Ar ratio did not strongly affect the metal ion composition. Film crystalline structure and dielectric properties ...


Journal of Applied Physics | 1998

Control of diamond film microstructure by Ar additions to CH4/H2 microwave plasmas

D. Zhou; Dieter M. Gruen; Lu Chang Qin; Thomas G. McCauley; A. R. Krauss

The transition from microcrystalline to nanocrystalline diamond films grown from Ar/H2/CH4 microwave plasmas has been investigated. Both the cross-section and plan-view micrographs of scanning electron microscopy reveal that the surface morphology, the grain size, and the growth mechanism of the diamond films depend strongly on the ratio of Ar to H2 in the reactant gases. Microcrystalline grain size and columnar growth have been observed from films produced from Ar/H2/CH4 microwave discharges with low concentrations of Ar in the reactant gases. By contrast, the films grown from Ar/H2/CH4 microwave plasmas with a high concentration of Ar in the reactant gases consist of phase pure nanocrystalline diamond, which has been characterized by transmission electron microscopy, selected area electron diffraction, and electron energy loss spectroscopy. X-ray diffraction and Raman spectroscopy reveal that the width of the diffraction peaks and the Raman bands of the as-grown films depends on the ratio of Ar to H2 in...


Journal of Applied Physics | 1997

SYNTHESIS AND ELECTRON FIELD EMISSION OF NANOCRYSTALLINE DIAMOND THIN FILMS GROWN FROM N2/CH4 MICROWAVE PLASMAS

D. Zhou; A. R. Krauss; Lu Chang Qin; Thomas G. McCauley; Dieter M. Gruen; T. D. Corrigan; R. P. H. Chang; Hubert Gnaser

Nanocrystalline diamond films have been synthesized by microwave plasma enhanced chemical vapor deposition using N2/CH4 as the reactant gas without additional H2. The nanocrystalline diamond phase has been identified by x-ray diffraction and transmission electron microscopy analyses. High resolution secondary ion mass spectroscopy has been employed to measure incorporated nitrogen concentrations up to 8×1020 atoms/cm3. Electron field emission measurements give an onset field as low as 3.2 V/μm. The effect of the incorporated nitrogen on the field emission characteristics of the nanocrystalline films is discussed.


Journal of Applied Physics | 2001

Electron field emission for ultrananocrystalline diamond films

A. R. Krauss; O. Auciello; M. Q. Ding; Dieter M. Gruen; Y.Y. Huang; Victor V. Zhirnov; E. I. Givargizov; A. Breskin; R. Chechen; E. Shefer; V. Konov; S. Pimenov; A. Karabutov; A.T. Rakhimov; N. V. Suetin

Ultrananocrystalline diamond (UNCD) films 0.1–2.4 μm thick were conformally deposited on sharp single Si microtip emitters, using microwave CH4–Ar plasma-enhanced chemical vapor deposition in combination with a dielectrophoretic seeding process. Field-emission studies exhibited stable, extremely high (60–100 μA/tip) emission current, with little variation in threshold fields as a function of film thickness or Si tip radius. The electron emission properties of high aspect ratio Si microtips, coated with diamond using the hot filament chemical vapor deposition (HFCVD) process were found to be very different from those of the UNCD-coated tips. For the HFCVD process, there is a strong dependence of the emission threshold on both the diamond coating thickness and Si tip radius. Quantum photoyield measurements of the UNCD films revealed that these films have an enhanced density of states within the bulk diamond band gap that is correlated with a reduction in the threshold field for electron emission. In additio...


Applied Physics Letters | 1998

Growing carbon nanotubes by microwave plasma-enhanced chemical vapor deposition

Lu Chang Qin; D. Zhou; A. R. Krauss; Dieter M. Gruen

A processing route has been developed to grow bundles of carbon nanotubes on substrates from methane and hydrogen mixtures by microwave plasma-enhanced chemical vapor deposition, catalyzed by iron particles reduced from ferric nitrate. Growth takes place at about 900 °C leading to nanotubes with lengths of more than 20 μm and diameters on the nanometer scale.


Journal of Applied Physics | 1994

Buckyball microwave plasmas: Fragmentation and diamond-film growth

Dieter M. Gruen; Shengzhong Liu; A. R. Krauss; Xianzheng Pan

Microwave discharges (2.45 GHz) have been generated in C60‐containing Ar. The gas mixtures were produced by flowing Ar over fullerene‐containing soot at a variety of temperatures. Optical spectroscopy shows that the spectrum is dominated by the d 3Πg–a  3Πu Swan bands of C2 and particularly the Δv=−2, −1, 0, +1, and +2 sequences. These results give direct evidence that C2 is in fact one of the products of C60 fragmentation brought about, at least in part, by collisionally induced dissociation. C60 has been used as a precursor in a plasma‐enhanced chemical vapor deposition experiment to grow diamond‐thin films. The films, grown in an Ar/H2 gas mixture (0.14% carbon content, 100 Torr, 20 sccm Ar, 4 sccm H2, 1500 W, 850 °C substrate temperature) were characterized with scanning electron microscopy, x‐ray diffraction, and Raman spectroscopy. The growth rate was found to be ∼0.6 μm/h. Assuming a linear dependence on carbon concentration, a growth rate at least six times higher than commonly observed using meth...

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Dieter M. Gruen

Argonne National Laboratory

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O. Auciello

Argonne National Laboratory

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D. M. Gruen

Argonne National Laboratory

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E. A. Irene

University of North Carolina at Chapel Hill

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Thomas G. McCauley

Argonne National Laboratory

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J. Im

Argonne National Laboratory

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A. Erdemir

Argonne National Laboratory

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D. Zhou

Argonne National Laboratory

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Y. Gao

University of North Carolina at Chapel Hill

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