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Journal ArticleDOI

Silicon carbide nanoparticles for advanced materials produced in radio frequency modulated glow discharges

01 Sep 1997-Vacuum (Pergamon)-Vol. 48, pp 665-668
TL;DR: In this article, a nanometric powder of silicon carbide has been produced in a radiofrequency square wave-modulated glow discharge of SiH 4 and CH 4 gases, and the chemical composition of the powder was determined by X-ray photoelectron spectroscopy.
About: This article is published in Vacuum.The article was published on 1997-09-01. It has received 8 citations till now. The article focuses on the topics: Glow discharge & Electron diffraction.
Citations
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Journal ArticleDOI
TL;DR: In this article, the influence of silicon and oxygen content on the structure of amorphous diamond-like carbon films are discussed and the chemical composition and bonding between the constituents are investigated.

62 citations

Journal ArticleDOI
TL;DR: In this paper , a comprehensive overview on the synthesis, properties and potential applications of SiC nanoparticles is presented, with the classification of solid phase, liquid phase and vapor phase processes.

17 citations

Journal ArticleDOI
01 Jan 1999-Vacuum
TL;DR: In this article, a SiC nanometric powder has been obtained in square-wave modulated radiofrequency glow discharges from CH 4 and SiH 4 gas mixtures, and the effects on the structure of the powder were examined by FTIR, EA, XPS and from optical transmittance measurements.

14 citations

Book ChapterDOI
01 Jan 2000
TL;DR: In this paper, the formation of particles in low-temperature, low-pressure plasmas is discussed and various technological aspects of the formation and characterization of the powders are discussed.
Abstract: Publisher Summary This chapter shows that low-pressure, low-temperature plasmas may generate a high particle nucleation rate and that they can allow for control of the composition, size, and atomic structure of the particles. These plasmas can produce nanometric particles of different composition, size, size distribution, and microstructure, depending on the discharge conditions. Besides the plasma parameters, modulation of the discharge and control of the duration of the plasma-on time can determine particle features. Results on the formation of powders of different alloys have also been presented. The scientific context of the formation of particles in low-temperature, low-pressure plasmas is reviewed. The basic studies of particles in interstellar space, the concern of the microelectronics industry about their contamination effect, the recent interest in nanostructured ceramics, and the new field of plasma crystals are also described. The various technological aspects of the formation and characterization of the powders are discussed. Detailed reports on the strong light emission observed in silicon nanoparticles produced in an rf discharge at low pressures showed that its origin is blackbody emission. In spite of using low laser intensities, nanoparticles heat up as a result of their low efficiency for dissipating heat through conduction between particles. This effect may be, in some cases, responsible for the light emission in other nanostructured materials.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reported the production of SiN nanopowder at room temperature and low pressure by RF glow discharge decomposition of SiH 4 and NH 3 gases, where the RF power was modulated at 0.5 Hz with a duty cycle of 20% in order to control the size of the expelled particles.
Abstract: Square-wave modulated radio frequency (RF) plasmas have been shown to be a suitable source of nanometric size powder with high purity and controllable nanostructure. This paper reports the production of SiN nanopowder at room temperature and low pressure by RF glow discharge decomposition of SiH 4 and NH 3 gases. The RF power was modulated at 0.5 Hz with a duty cycle of 20% in order to control the size of the expelled particles. A study of the particle formation process using in-situ monitoring of the RF dissipated power is presented. Transmission electron microscopy showed a narrow size distribution of spherical particles from 25 to 45 nm and their electron diffraction provided evidence of a short range order in Si or SiN units depending on the precursor gas mixture. Analysis by Fourier transform infrared spectroscopy revealed the presence of SiN, NH and SiH bonds and the elemental analysis of the powder determined its chemical composition.

10 citations

References
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01 Jan 1995

2,448 citations

Journal ArticleDOI
TL;DR: The sol-gel process opens the possibility of combining inorganic and organic units on a molecular or nanosized level as discussed by the authors, and the flexible chemical approach of tailoring inorganic structures as well as organic polymeric structures in combination with the new concept of incorporation of nanoscaled metal oxide particles open the possibility to achieve new multifunctional materials like extremely high scratch resistance, antisoiling properties, antifogging properties and corrosion-inhibitant coatings on metals.
Abstract: The sol-gel process opens the possibility of combining inorganic and organic units on a molecular or nanosized level. The flexible chemical approach of tailoring inorganic structures as well as organic polymeric structures in combination with the new concept of incorporation of nanoscaled metal oxide particles opens the possibility of achieving new multifunctional materials like extremely high scratch resistance, antisoiling properties, antifogging properties and corrosion-inhibitant coatings on metals.

111 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a Brownian free molecule coagulation model to determine the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering.
Abstract: To determine self-consistently the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering was used. Cross-polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135 degrees and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross-polarization intensities is accompanied by low-frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log-normal particle size distribution. (C) 1996 American Institute of Physics.

90 citations

Journal ArticleDOI
TL;DR: The surface composition and bonding of a wide variety of silicon carbide powders and whiskers have been characterized by x-ray photoelectron spectroscopy (XPS) as discussed by the authors.
Abstract: The surface composition and bonding of a wide variety of silicon carbide powders and whiskers have been characterized by x-ray photoelectron spectroscopy (XPS). Ultrafine SiC powders, grown by a radio frequency plasma process, have been shown to exhibit graphitic carbon and a thin suboxide coating. Whiskers of SiC, grown in a vapor-liquid-solid or proprietary commercial process, were generally covered by heavier oxides than the powders and to a variable degree showed silica-like bonding. Most of the materials were subject to sample charging. Procedures were developed to estimate these charging effects and interpret the complete catalog of XPS spectra from these materials with respect to Fermi-level assignments. Charge independent quantities, such as oxygen Auger parameter and O(1s)–Si(2p) peak position difference, were found to agree with accepted values in the literature while exhibiting trends consistent with suboxide and silica bonding assignments. The data give a broad basis for understanding the feedstock surface chemistry which is involved during fabrication of monolithic or composite silicon carbide materials.

72 citations

Journal ArticleDOI
TL;DR: In this paper, the discharge power is derived by subtracting losses from the total power reading, which can be used as an aid in the scaling of system sizes, and this discharge power exhibits interesting behavior as the pressure is varied, at constant applied rf voltage.
Abstract: Radio frequency (rf) sputtering is used for the deposition and etching of thin layers. In both cases the target etch rate must be controlled, and often power input has been used as one of the controlling parameters. An earlier paper has shown that the applied rf target voltage (V pp) was a more useful parameter, and here new data is presented which indicates that the peak‐to‐peak voltage remains the preferable parameter for both etch rate control and in transferring between machines. However, a new method is described here which obtains the discharge power by subtracting losses from the total power reading. This discharge power is shown to be related to etch rates, and can thus be used as an aid in the scaling of system sizes. In addition, this discharge power exhibits interesting behavior as the pressure is varied, at constant applied rf voltage. Three main regions are evident when etching Si with CF4: at low pressures directional ion‐induced etching is obtained; in an intermediate region the input power rises rapidly with pressure and the etching is less directional resulting in overhang profiles; and at high pressures an isotropic etching component results in undercut profiles. The two extreme regions correlate with the commonly identified regimes of: (a) low power input, low pressure reactive sputter etching, and (b) high power input, high pressure plasma etching.

51 citations