Showing papers on "Fabrication published in 1972"

Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells

Abstract: An investigation of the characteristics and behavior of 10 ohm-cm silicon cells having abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is detailed. The study showed that 10 ohm-cm back-surface-field cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back-surface-field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.

Ion bombardment fabrication of optical waveguides using electron resist masks

Abstract: Fabrication of a circular strip waveguide by ion implantation of fused silica through a mask made by electron‐beam exposure of polymethylmethacrylate (PMMA) is described. This technique has an advantage in its simplicity and the small number of processing steps involved. Guidance of 0.6328‐μm light from a He–Ne laser through the guide is demonstrated.

Technique for the fabrication of a millimeter wave beam lead schottkybarrier device

Abstract: A technique is described for the fabrication of a novel planar millimeter wave beam lead Schottky barrier device. The inventive technique involves the growth of a 6 to 7 micron layer of epitaxial gallium arsenide doped to 3 to 5 X 1018 atoms/cc on a semi-insulating gallium arsenide substrate by the arsenic trichloride-gallium-hydrogen vapor transport technique. Following, the epitaxial layer is etched in the same ambient by adding helium and establishing a doping level of 5 X 1015 to 2 X 1017 atoms/cc. Growth of a 0.1 to 0.2 micron thick layer of gallium arsenide is then effected. The technique results in the formation of an abrupt doping profile and in a device manifesting enhanced frequency.

Metal-insulator-semiconductor structures having reduced junction capacitance and method of fabrication

Abstract: Metal-insulator-semiconductor structures characterized by reduced junction capacitance and methods of fabrication are disclosed. A substantially intrinsic region beneath the junction is formed by implanting selected ions. The ion implantation does not produce lateral diffusion of conventionally formed junctions, and therefore breakdown and packing density are not changed. The substantially intrinsic region does, however, increase the space charge region of the adjacent junction, thus reducing the effective capacitance. In the preferred method of fabrication, ions are implanted using the same mask employed in forming the p-n junction.

Method for the fabrication of miniature anodes for tantalum capacitors by dipping in a viscous slurry

Abstract: A NEW TECHNIQUE OF CONTACTING THE ENDS OF FILM FORMING METAL WIRE IN A SLURRY OF FILM FORMING METAL POWDER IN A LIQUID, DRYING THE COATING, AND SINTERING THE ADHERING POWDER TO THE IWRE RESULTS IN ANODES SUITABLE FOR FABRICATION INTO CAPACITORS. D R A W I N G

Method of fabrication of composite anode for rotating-anode x-ray tubes

Abstract: Disclosed is an improved composite anode for rotating-anode x-ray tubes and an improved method of fabrication thereof.

Two-phase m.n.o.s. charge-coupled device

Abstract: A 2-phase charge-coupled device (c.c.d.) is proposed. It makes use of charge storage in an m.n.o.s. structure to define in the silicon substrate the asymmetrical potential wells required for unidirectional charge flow. The fabrication and operation of the device are described. The structure permits substantial simplification of the fabrication method as compared with other c.c.d.s.

Strain sensitive properties of threshold switch devices

Abstract: A blend of integrated circuit manufacturing techniques and rf sputtering techniques has resulted in TeAs-XXX threshold devices sustaining 100 million switchings. The fabrication and properties of these devices are outlined in this paper. Observations of space charge effects and the influence of strain on the switching properties of these devices are also reported.

In-space fabrication of thin-film structures

Abstract: A conceptual study of physical vapor-deposition processes for in-space fabrication of thin-film structures is presented. Potential advantages of in-space fabrication are improved structural integrity and surface reflectivity of free-standing ultra-thin films and coatings. Free-standing thin-film structures can find use as photon propulsion devices (solar sails). Other applications of the concept involve free-standing shadow shields, or thermal control coatings of spacecraft surfaces. Use of expendables (such as booster and interstage structures) as source material for the physical vapor deposition process is considered. The practicability of producing thin, textured, aluminum films by physical vapor deposition and subsequent separation from a revolving substrate is demonstrated by laboratory experiments. Heating power requirement for the evaporation process is estimated for a specific mission.

Analysis of epitaxial layer thickness variability in the fabrication of high performance bipolar transistors

Abstract: Measurements indicate that a thickness variation of approximately 7·0 per cent (2σ) can be expected from modern epitaxial reactors. This epitaxial layer thickness variability, in conjunction with the technique of designing into a transistor collector junction and buried layer interference, will often produce problems of fabrication reproducibility. Statistical calculations are presented to demonstrate some fabrication difficulties that are mathematically attributable to this thickness variability. Problems arising from simple space-charge layer interference are compared with those arising from deep penetration of the collector junction into its buried layer.

Technique for the Preparation of Ge and Si Field‐Emission Cathodes

Abstract: Methods are described for the fabrication of Ge and Si field‐emission cathodes by grinding of single crystal, oriented blanks of the semiconductor followed by electrolytic etching. Highly symmetrical, well formed emitters result. A glow discharge cleaning and shaping technique is presented that leads to atomically clean, well developed surfaces in the field‐emission microscope.

Development of wire drawing processes for refractory metal fibers

Abstract: Fabrication schedules were developed for producing wire, 0.25 mm to 0.51 mm diameter, from the refractory metal alloys ASTAR-811C, B-88 and W-Hf-C. Tensile properties were evaluated at room temperature and up to 1204 C. Also, the stress rupture properties of the alloys at 1093 C were determined. W-Hf-C and B-88 were found to have the best mechanical properties on a strength to density basis. The fabrication schedules for producing wire from these two alloys were further improved with regards to the wire quality and material yield under the optimization of fabrication schedule.

Photomasks and method of fabrication thereof

Abstract: Photomasks and method of fabrication thereof, whereby a thin layer of germanium is deposited to a substrate which may be then etched in a pattern to provide a photomask or information storage device. In the fabrication method, a substrate is carried by belt through a first inert gas curtain into a furnace containing a mixture of suitable gases for causing the deposition of germanium onto the heated substrate, and there outward through a second inert gas curtain into a cooling region. The use of a germanium film for a mask blank results in a mask which is reasonably transparent to visible light but substantially opaque to ultravoilet light, and which may be deposited on to and removed from various substrates including glass using etchants which do not attack the substrate material.

Technique for the fabrication of an air isolated crossover

Abstract: A TECHNIQUE IS DESCRIBED FOR THE FABRICATION OF AN AIR ISOLATED CROSSOVER INCLUDING A SUPPLEMENTARY INSULATING LAYER WHICH IS COMPATIBLE WITH THE CROSSOVER PROCESS AND THE THIN FILM CONDUCTOR SYSTEM UTILIZED IN ITS FABRICATION THE SUPPLEMENTARY INSULATING LAYER COMPRISES SILICON DIOXIDE AND IS DEPOSITED DURING THE PROCESSING SEQUENCE BY CONVENTIONAL EVAPORATION OR OTHER DEPOSITION TECHNIQUES. THE RESULTANT DOUBLE DIELECTRIC PERMITS FREE MOVEMENT OF BEAMS DURING TEMPERATURE CYCLING, AVOIDS EDGE DEPOSITION PROBLEMS DUE TO SHADOWING ON SHARP EDGES OF THE DIELECTRIC AND MAKES PINHOLES IN THE DIELECTRIC INNOCUOUS.

Develop Fabrication/Processing Techniques for High Temperature Advanced Composites for use in Aircraft Structures

Abstract: : The objectives of this program were to place polyimide matrix advanced composite processing technology on a production basis, and to demonstrate its acceptability for structural applications by fabrication and test of representative structure. Under this program polyimide matrix advanced composites were cured in a one shift autoclave operations (-8 hours) at 350 F and 200 psi maximum while maintaining epoxy matrix-type properties. These process parameters were confirmed by the successful fabrication and test of an F-4 polyimide rudder, which demonstrated the flight worthiness of thin gauge boron and graphite/polyimide in this type structure. Design allowable data for tension, compression, and inplane shear were developed at both room temperature and 550 F.

Fabrication and performance of GaAs millimeter-wave impatts

Abstract: A recently developed procedure, incorporating both preferential electrolytic etching for wafer thinning and electroplating for formation of a heat sink has been applied to the fabrication of Ka-band (26.5-40 GHz) GaAs IMPATTS. The technique is an extension of the work recently reported on 50-60 GHz silicon diodes. Both epitaxially-grown GaAs-pn juction and Schottky barrier (Pt and Cr) diodes have been fabricated. Uniform GaAs structures as thin as 4µm have been produced on plated Cu and Au supports.

Fabrication of fuel pin assemblies, phase 3

Abstract: Five full size and eight reduced length fuel pins were fabricated for irradiation testing to evaluate design concepts for a fast spectrum lithium cooled compact space power reactor. These assemblies consisted of uranium mononitride fuel pellets encased in a T-111 (Ta-8W-2Hf) clad with a tungsten barrier separating fuel and clad. Fabrication procedures were fully qualified by process development and assembly qualification tests. Detailed specifications and procedures were written for the fabrication and assembly of prototype fuel pins.