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])...
TL;DR: In this article, a series of calculations using semi-empirical molecular orbital PM3 and density-functional theories was used to optimize the interface structure of a large cluster model in order to reveal the interface strain and bonding.
Abstract: To pursue single-crystal diamond growth on silicon substrates, the mechanism of diamond nucleation and growth must be well understood. For this purpose, step-by-step depositions of hydrocarbon species on a silicon (001)-(2×1) surface were simulated based on a series of calculations using semi-empirical molecular orbital PM3 and density-functional theories. Molecular mechanics was also used to optimize the interface structure of a large cluster model in order to reveal the interface strain and bonding. It is shown that diamond can be coincidentally built on the silicon (001) surface in spite of the 3:2 lattice mismatch. Issues such as residual lattice mismatch, nucleation mode and surface roughness relating to single-crystal diamond growth are discussed.
TL;DR: In this article, powder particles are incorporated in device quality a-Si:H films and they are found to be of ∼200 nm in diameter and are more fragile than the rest of the film.
Abstract: We have found powder particles incorporated in device quality a-Si:H films. Investigations carried out by atomic force microscopy (AFM) have shown that these particles are of ∼200 nm in diameter and are more fragile than the rest of the film. SiH-stretching absorption bands in a-Si:H films consisted of two bands with frequencies of about 2020 and ∼2100 cm−1. Both peaks shift to higher frequencies with the increase of a volume fraction of powder particles. Taking into account the predictions of the chemical induction model, we conclude that this shift is due to high local hydrogen content in the powder particles which also explains their low hardness. It was found that the density of valence band tail states increases with the enlargement of particle surface areas. At the same time, the Urbach energy and the optical gap remain in the ranges of 50 to 70 meV and of 1.7 to 1.8 eV, respectively, indicating the good electronic properties of investigated films.
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.