Abstract: The process comprises the following steps: (1) forming a glass sheet which defines a substrate layer for the solar cell product; (2) forming a diffusion barrier layer on at least one surface of the substrate; (3) forming a first electrically-conductive layer on the diffusion barrier, the first electrically-conductive layer being a first electrode in the solar cell product; (4) depositing small-grain polycrystalline silicon in a thin film, i.e., 10-100 micrometers, on the first electrode layer; (5) recrystallizing, typically by heating, the deposited polycrystalline silicon until it reforms into large-grain polycrystalline or single-crystal silicon; (6) forming a PN junction in the recrystallized silicon layer; and (7) forming a second electrically-conductive layer on the recrystallized silicon layer, the second electrically-conductive layer being a second electrode in the solar cell product. The solar cell product produced by the above-process may be fabricated in large surface area configurations, suitable for terrestrial as well as extra-terrestrial use, at relatively low cost.

Abstract: Steel is the most economical substrate for the deposition of silicon. At temperatures used for the chemical vapor deposition of silicon, however, a barrier layer must be used to prevent the diffusion of iron from the substrate into the silicon layer. Tungsten was found to be ineffective as a diffusion barrier when silicon was deposited by the thermal decomposition of silane at 900/sup 0/C and above. Borosilicate deposited by the oxidation of a silicon-diborane mixture was found to be an effective barrier at temperatures up to 1150/sup 0/C. Silicon layers deposited at low temperatures and high rates consist of small crystallites with a strong preferred (110) orientation, while those deposited at high temperatures and low rates consist of larger crystallites with more random orientation. Silicon p--n junctions deposited on borosilicate/steel substrates show poor electrical characteristics because of the high concentration of grain boundaries, and solar cells have low conversion efficiencies.

Abstract: A chemical compatibility study was conducted between SiC filament and the following P/M matrix alloys: Waspaloy, Hastelloy-X, NiCrAlY, Ha-188, S-57, FeCrAlY, and Incoloy 800. None of the couples demonstrated sufficient chemical compatibility to withstand the minimum HIP consolidation temperatures (996 C) or intended application temperature of the composite (982 C). However, Waspaloy, Haynes 188, and Hastelloy-X were the least reactive with SiC of the candidate alloys. Chemical vapor deposited tungsten was shown to be an effective diffusion barrier between the superalloy matrix and SiC filament providing a defect-free coating of sufficient thickness. However, the coating breaks down when the tungsten is converted into intermetallic compounds by interdiffusion with matrix constituents. Waspaloy was demonstrated to be the most effective matrix alloy candidate in contact with the CVD tungsten barrier because of its relatively low growth rate constant of the intermediate compound and the lack of formation of Kirkendall voids at the matrix-barrier interface. Fabrication methods were developed for producing panels of uniaxial and angle ply composites utilizing CVD tungsten coated filament.

Abstract: A chemical compatibility study was conducted between SiC filament and the following P/M matrix alloys: Waspaloy, Hastelloy-X, NiCrAlY, Ha-188, S-57, FeCrAlY, and Incoloy 800. None of the couples demonstrated sufficient chemical compatibility to withstand the minimum HIP consolidation temperatures (996 C) or intended application temperature of the composite (982 C). However, Waspaloy, Haynes 188, and Hastelloy-X were the least reactive with SiC of the candidate alloys. Chemical vapor deposited tungsten was shown to be an effective diffusion barrier between the superalloy matrix and SiC filament providing a defect-free coating of sufficient thickness. However, the coating breaks down when the tungsten is converted into intermetallic compounds by interdiffusion with matrix constituents. Waspaloy was demonstrated to be the most effective matrix alloy candidate in contact with the CVD tungsten barrier because of its relatively low growth rate constant of the intermediate compound and the lack of formation of Kirkendall voids at the matrix-barrier interface. Fabrication methods were developed for producing panels of uniaxial and angle ply composites utilizing CVD tungsten coated filament. (Author) (GRA)

Abstract: A thin film circuit is provided with multilayer conducting traces on an insulating substrate, which is of ceramic or glass and can possibly be provided with further layers. The conducting traces are produced by applying an adhesive layer and avaporating a copper layer, and then a further copper and gold layer are applied by electroplating. The gold layer is applied directly on the copper layer, omitting a diffusion barrier layer, and then the film circuit is heat trated at a temperature higher than the highest used during subsequent processes or met in operation. Copper diffuses through the gold layer up to its surface, and oxide layer produced on the surface during heat treatment in normal atmosphere, or after treatment in a protective gas, is removed by etching.

Abstract: 1. A thin (about 40 A thick) layer of silicon carbide on a carbon fiber in contact with nickel acts as a diffusion barrier inhibiting the processes of surface defect formation on the fiber and loss of strength of the fiber only up to temperatures of 700–800°C during exposure for up to 50 h. 2. Raising the temperature above 800°C brings about intense dissolution of the coating and fiber in the nickel, which is accompanied by activated recrystallization of the fiber and catastrophic loss of its strength. Under such conditions a silicon carbide coating no longer constitutes an effective diffusion barrier. 3. The application of a silicon carbide layer to a carbon fiber increases the latter's resistance to attack by oxidizing atmospheres, which may facilitate the process of formation of a nickel-carbon-fiber composite and raise the maximum permissible operating temperature of the material.

Abstract: Compact coatings of ''amorphous'' boron were deposited on a smooth surface of a substrate such as graphite, refractory metals, iron, and stainless steel using the reduction of boron trichloride by hydrogen. With a constant surface temperature, and a low deposition efficiency, a constant thickness is obtained if transport limitations are avoided in all points of the surface. Extension of the results is proposed for the deposition on larger surfaces and complex shaped substrates. The rate of deposition was studied at temperatures ranging from 950 to 1200$sup 0$C. The apparent activation energy is found equal to 31.4 kcal/mole. Adherence and absence of cracks are a function of the specific nature of the substrates. The most satisfactory coatings were obtained on graphite and on refractory metals of group Vb, iron and stainless steel. On iron and stainless steel, a diffusion barrier was first deposited by pack cementation, which avoids the transport of the metals and slows down the boron diffusion. Boron morphology regularity is shown to be a function of nucleation. (auth)

Abstract: To retard failure of gold plated copper parts by diffusion of copper to the gold surface, a layer of nickel is frequently used between the copper and gold as a diffusion barrier. To evaluate the mechanisms whereby the nickel retards the motion of copper atoms to the gold surface, planar tri-couples of Cu/Ni/Au were prepared by electroplating nickel and gold layers on OFHC copper coupons. Diffusion anneals were carried out at temperatures from 150 to 750°C. A qualitative evaluation of diffusion behavior was provided by an electron microprobe utilizing X-ray wavelength dispersive analysis on polished cross sections. Results demonstrate that the nickel layer retards but does not block the transport of copper to the gold surface. Possible mechanisms for the anomalous buildup of copper at the gold/nickel interface and gold at the copper/nickel interface are discussed.