Production of nanometric particles in radio frequency glow discharges in mixtures of silane and methane
01 Mar 1996-Journal of Vacuum Science and Technology (American Institute of Physics)-Vol. 14, Iss: 2, pp 567-571
TL;DR: In this paper, the a−Si1−xCx:H powders were obtained from different precursor gas mixtures, from R=0.05 to R=9, where R=[SiH4]/([SiH 4]+[CH4])...
Abstract: The formation of silicon particles in rf glow discharges has attracted attention due to their effect as a contaminant during film deposition or etching. However, silicon and silicon alloy powders produced by plasma‐enhanced chemical vapor deposition (PECVD) are promising new materials for sintering ceramics, for making nanoscale filters, or for supporting catalytic surfaces. Common characteristics of these powders are their high purity and the easy control of their stoichiometry through the composition of the precursor gas mixture. Plasma parameters also influence their structure. Nanometric powders of silicon–carbon alloys exhibiting microstructural properties such as large hydrogen content and high surface/volume ratio have been produced in a PECVD reactor using mixtures of silane and methane at low pressure (<1 Torr) and low frequency square‐wave modulated rf power (13.56 MHz). The a‐Si1−xCx:H powders were obtained from different precursor gas mixtures, from R=0.05 to R=9, where R=[SiH4]/([SiH4]+[CH4])...
18 Aug 2014
TL;DR: In this paper, microwave plasmas are used for the synthesis of inorganic materials and material groups, including bare Fe2O3 nanoparticles, core/shell ceramic/organic shell nanoparticles and Sn-based nanocomposites.
Abstract: In this review, microwave plasma gas-phase synthesis of inorganic materials and material groups is discussed from the application-oriented perspective of a materials scientist: why and how microwave plasmas are applied for the synthesis of materials? First, key players in this research field will be identified, and a brief overview on publication history on this topic is given. The fundamental basics, necessary to understand the processes ongoing in particle synthesis—one of the main applications of microwave plasma processes—and the influence of the relevant experimental parameters on the resulting particles and their properties will be addressed. The benefit of using microwave plasma instead of conventional gas phase processes with respect to chemical reactivity and crystallite nucleation will be reviewed. The criteria, how to choose an appropriate precursor to synthesize a specific material with an intended application is discussed. A tabular overview on all type of materials synthesized in microwave plasmas and other plasma methods will be given, including relevant citations. Finally, property examples of three groups of nanomaterials synthesized with microwave plasma methods, bare Fe2O3 nanoparticles, different core/shell ceramic/organic shell nanoparticles, and Sn-based nanocomposites, will be described exemplarily, comprising perspectives of applications.
01 May 2008
TL;DR: In this paper, a plasma processing apparatus for producing a set of Group IV semiconductor nanoparticles from a precursor gas is disclosed, which includes an outer dielectric tube, the outer tube including an outer tube inner surface and an outer-tube outer surface, wherein the outer-to-outer inner surface has an inner-surface etching rate.
Abstract: A plasma processing apparatus for producing a set of Group IV semiconductor nanoparticles from a precursor gas is disclosed. The apparatus includes an outer dielectric tube, the outer tube including an outer tube inner surface and an outer tube outer surface, wherein the outer tube inner surface has an outer tube inner surface etching rate. The apparatus also includes an inner dielectric tube, the inner dielectric tube including an inner tube outer surface, wherein the outer tube inner surface and the inner tube outer surface define an annular channel, and further wherein the inner tube outer surface has an inner tube outer surface etching rate. The apparatus further includes a first outer electrode, the first outer electrode having a first outer electrode inner surface disposed on the outer tube outer surface. The apparatus also includes a first central electrode, the first central electrode being disposed inside the inner dielectric tube, the first central electrode further configured to be coupled to the first outer electrode when a first RF energy source is applied to one of the first outer electrode and the first central electrode; and a first reaction zone defined between the first outer electrode and the central electrode.
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.
Abstract: SiC nanometric powder has been obtained in square-wave modulated radiofrequency glow discharges from CH 4 and SiH 4 gas mixtures. Chemical and structural characterization revealed that the as-deposited SiC:H powder underwent spontaneous oxidation when exposed to atmosphere. To stabilise the powder chemically, we carried out a thermal treatment under vacuum (10 −4 Pa) consisting of heating to 800°C (20°C/min). The effects on the structure of the powder were examined by FTIR, EA, XPS and from optical transmittance measurements. They can be summarized as follows: dehydrogenation of the powder that induces the formation of a SiC carbidic network and chemical stability under atmospheric conditions, further confirmed by exposure to air for more than 6 months. In addition, TEM images showed that the annealed powder presented a short-range order in β -SiC units, but there was no evidence of size changes due to sinterization or compactaction phenomena.
TL;DR: Amorphous silicon powder has been produced in a tubular glow discharge reactor as discussed by the authors, where reaction were done using SiCl4 discharges of a mixture of hydrogen and helium at atmospheric pressure.
Abstract: Amorphous silicon powder has been produced in a tubular glow discharge reactor. Reaction were done using SiCl4 discharges of a mixture of hydrogen and helium at atmospheric pressure. Chemical and p...
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.
TL;DR: In this article, the origin of photoluminescence emitted by silicon powder produced by plasma-enhanced chemical vapor deposition is analyzed in view of the structural changes induced by laser annealing.
Abstract: The origin of the photoluminescence (PL) emitted by silicon powder produced by plasma-enhanced chemical vapor deposition is analyzed in view of the structural changes induced by laser annealing. Both, the Raman spectra and the PL signal are qualitatively different before and after this process. It involves some degree of recrystallization which can be deduced from the Raman spectra and also from a strong emission of H2. The analysis shows that the characteristic PL does not come from the as-grown state of the sample but from the annealed state.