Showing papers on "Chemical vapor deposition published in 1976"

Semiconductor Electrodes: V. The Application of Chemically Vapor Deposited Iron Oxide Films to Photosensitized Electrolysis

Abstract: The preparation of polycrystalline n-type Fe203 electrodes by the chemical vapor deposition (CVD) of iron oxide onto Ti and Pt substrates is reported. The behavior of these electrodes in aqueous solutions of different pH in the absence and presence of illumination is shown. Photoassisted electrolysis of water occurs at wavelengths longer than 400 nm and the current vs. wavelength curve for this process is compared to that of a CVD TiO2 electrode.

Refractive indices of TiO(2) films produced by reactive evaporation of various titanium-oxygen phases.

Abstract: In this paper experiments with reactive evaporation of the starting materials Ti, TiO, Ti(2)O(3), Ti(3)O(5), and TiO(2) to obtain nonabsorbing TiO(2) films are under discussion. For the starting materials TiO and Ti(3)O(5) the dependence of the TiO(2) film refractive index on the substrate temperature, oxygen pressure, and deposition rate was measured. For TiO dispersion curves of the resulting TiO(2) films as a function of the substrate temperature during film formation were determined. The successive evaporation of the different starting materials resulted in the formation of lambda/4 TiO(2) films with different refractive indices. This phenomenon was most obvious during the first evaporation. It disappeared after several evaporations in two groups of TiO2 films with different refractive indices. From the beginning only the starting materials Ti and Ti(3)O(5) resulted in TiO(2) films with constant refractive indices. The first material produced a high, the latter a lower film index. Depending on the number of evaporations performed, both types of TiO(2) films can be obtained with TiO. The films and residues in the crucibles were also subjected to chemical analyses. An attempt was made to explain the optical properties of the resulting TiO(2) films with regard to crystal structure, chemical composition, packing density influenced by the molecular composition of the vapor beam, chemical reaction with the crucible, substrate temperature, O(2) pressure, and deposition rate.

Low‐loss optical fibers prepared by plasma‐activated chemical vapor deposition (CVD)

Abstract: A modified method for the preparation of low‐loss optical fibers by means of chemical vapor deposition (CVD) techniques has been developed. In this method, a nonisothermal plasma is used to stimulate the reactions. Deposition of oxides then occurs only heterogeneously on the substrate. Results obtained by this method show optical losses well below 10 dB/km—having a minimum of 1.4 dB/km at a wavelength of 1050 nm—and a pulse dispersion of 0.8 ns/km.

Vapor deposition of single crystal gallium nitride

Abstract: Method of manufacturing gallium nitride crystals by reaction of galium halide and ammonia in which free hydrogen chloride is introduced into the reaction and deposition zones.

Metalorganic chemical vapor deposition of IVA-IVA compounds and composite

Abstract: A composite comprising a monocrystalline substrate and one or more layers or films of monocrystalline IVA-VIA compounds and/or alloys formed thereon by a chemical vapor deposition process. The composite is formed at a preferred temperature range of approximately 450°-650° C. The IVA-VIA layer(s) are produced by the pyrolysis of a gas mixture containing metalorganic compounds. Where single crystal metallic oxide substrates of rhombohedral structure, such as sapphire, (α-Al 2 O 3 ), or of cubic structure, such as magnesium aluminate (spinel), are used for the growth of monocrystalline lead-containing films such as Pb 1-x Sn x Te, a nucleation layer of lead is preferably formed on the substrate prior to the pyrolysis of the mixed gaseous reactants. Using the present process, epitaxial monocrystalline IVA-VIA compounds and/or alloys can be grown on inorganic metal oxide substrates, such as cubic and rhombohedral oxides, on alkali halides and IIA fluorides, and on II-VI and III-V compounds. The compositions of the films can be varied without removing the composites from the deposition apparatus by changing the ratio of the reactant gases and the reaction temperature. The conductivity type (n-type or p-type) of the films also can be controlled without removing the composites from the deposition apparatus by varying the reactant gas compositions and by incorporating a dopant into the reactant mixtures prior to pyrolysis.

Silicon carbide filaments and method

Abstract: A refractory substrate, which generally is graphite or carbon is overcoated with silicon carbide by chemical vapor deposition from gaseous sources of silicon and carbon. The deposition generally takes place in combination with hydrogen and the coating on the substrate generally has a thickness at least equal to the diameter of the substrate itself. A silicon carbide filament containing an inner and outer surface layer of carbon rich silicon carbide, together with a method of making the same, is described.

High‐performance solar cell material: n‐AlAs/p‐GaAs prepared by vapor phase epitaxy

Abstract: Solar cells with measured sea level sunlight power conversion efficiencies of 13–18% and areas of several cm2 have been prepared by vapor phase epitaxial growth of n‐AlAs on p‐GaAs substrates. The cells are provided with an antireflective passivating anodically grown coating and have much improved stability in the laboratory atmosphere.

Chemical Vapor Deposition of Tantalum Pentoxide Films for Metal‐Insulator‐Semiconductor Devices

Abstract: Thin amorphous Ta/sub 2/O/sub 5/ films were deposited by oxygen-assisted pyrolysis of tantalum dichloro-diethoxy-acetylacetonate. Index of refraction and the optical gap measurements of the films were in agreement with previous results. The d-c conduction mechanism appears to be bulk limited following the Poole-Frenkel mechanism with transition towards a space charge limited current at high current densities. The conduction level is high and breakdown voltage is low with respect to SiO/sub 2/ or Si/sub 3/N/sub 4/. The higher dielectric constant of Ta/sub 2/O/sub 5/ films could make them attractive in double layer insulator MIS devices.

Chemical vapor deposition methods of depositing zinc boro-silicated glasses

Abstract: An alkyl compound of zinc is reacted with alkyl compounds or alkoxyl compounds of boron and silicon in the presence of oxygen, thereby to deposit on a substrate zinc borosilicate glass film through a chemical vapor deposition process. The outlet nozzle of a raw material supply conduit for introducing the raw material compounds into a reaction zone is opened in the direction substantially in parallel with a surface of the substrate on which the glass film is to be deposited so that raw materials may be well mixed at the reaction zone. The glass film thus produced has a uniform thickness and a homogeneous composition of the constituents over an area at least of 40 mm extending from the nozzle and is suited for use as protection films for semiconductor devices and dielectric layer for a thin film capacitor on an industrial base.

Interaction of metal layers with polycrystalline Si

Abstract: Solid‐phase reactions of metal films deposited on 0.5‐μm‐thick polycrystalline layers of Si grown by chemical vapor deposition at 640 °C were investigated by MeV 4He backscattering spectrometry, glancing angle x‐ray diffraction, and SEM observations. For the metals Al, Ag, and Au, which form simple eutectics, heat treatment at temperatures below the eutectic results in erosion of the poly‐Si layer and growth of Si crystallites in the metal film. Crystallite formation is observed at T≳550 °C for Ag, T ≳400 °C for Al, and T ≳200 °C for Au films. For the metals Pd, Ni, and Cr, heat treatment results in silicide formation. The same initial silicides (Pd2Si, Ni2Si, and CrSi2), are formed at similar temperatures on single‐crystal substrates.

Effect of impurities on intrinsic stress in thin Ni films

Abstract: Intrinsic stress has been investigated in thin nickel films, ∠1000 A thick, deposited at approximately 25 A/s in an UHV system equipped with a variable leak valve. The residual gas pressure during deposition could be varied from 10−4 to 10−6 Pa. The cantilevered beam technique was used for measuring the film force per unit width as a function of film thickness. A new method, based on single slit diffraction, was developed for observing the substrate deflection. The stresses were tensile, and the average values decreased from 9.3×109 dynes/cm3 with 5.4 at.% total impurities, to 4.2×109 dynes/cm2 with 10.1 at.% impurities. The film impurity concentrations, determined from AES depth‐profile data, showed a correlation with the incremental stress as a function of film thickness. The major impurities were O and W from the evaporation filament, rather than the residual gasses, and film impurity content increased with filament outgassing time and power prior to evaporation. The films were examined with electron m...

Synthesis and stability of Nb3Ge made by electron‐beam codeposition

Abstract: Niobium‐germanium (Nb‐Ge) films which remain superconducting up to about 22.5 °K have been prepared using high‐rate (33–133 A/sec) electron‐beam codeposition. The presence of oxygen in the deposition chamber is necessary for stabilizing the high‐Tc A15 phase. Analysis of Nb‐Ge films shows that oxygen extends, with some temperature dependence, the Ge‐rich range of the A15 phase with an accompanying decrease in the lattice constant. An amorphous component in the films is first detected below a deposition temperature of 800 °C. It increases rapidly at lower temperatures and becomes dominant at about 600 °C. The A15 phase diagram was determined for the first time for temperatures below 875 °C.

On the Enhancement of Silicon Chemical Vapor Deposition Rates at Low Temperatures

Abstract: This paper presents a conceptual model to explain the dopant gas, (B/sub 2/H/sub 6/, PH/sub 3/, AsH/sub 3/) effects on the rate of Si chemical vapor deposition Predictions of the model are compared with observations on SiH/sub 4/, SiCl/sub 4/ and also CH/sub 4/; the agreement is encouraging, and recommendations are made for further work to test the model (DLC)

Chemical Vapor Deposition of Amorphous Boron on Massive Substrates

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)

Control of vapor deposition

Abstract: An arrangement for regulating the vapor deposited layer build-up in the production of deposited optically active thin layers on substrates in a vacuum. The optical characteristics of the deposited layer are measured continuously and the measurements are converted into proportional electrical signals. These signals are differentiated twice, with the second derivative serving to provide the zero-axis crossings of the signals. The vapor deposition process is interrupted dependent on the zero-axis crossings.

Chemical Vapor Deposition of Silicon Nitride

Abstract: : Experimental work during the past year has established the basic processing outlines for the deposition of crystalline alpha-Si3N4 plates and dome geometries. Preliminary correlations between critical processing variables and microstructure have been established. Property evaluations of deposits include: flexure strength, Young's moduli, thermal expansion, electromagnetic transmittance and reflectance, microhardness and fracture toughness deduced from identation and grooved double-cantilever beam experiments. (Author)

Si3 N4 Coated crucible and die means for growing single crystalline silicon sheets

Abstract: Mechanical components, e.g. die and/or crucible or the like structures with which single silicon crystals are grown from the melt as shaped articles in thin sheet or ribbon geometry, are advantageously comprised, for their material of construction, of a suitable thermally stable and inert foundation substrate coated or provided on at least the silicon-contacting surface(s) thereof with a thin, uniform, integral surface layer deposit of pyrolitic silicon nitride (Si3 N4) obtained by the chemical vapor deposition (i.e., "CVD") technique.

Chemical vapor deposition reactor

Abstract: An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials

Induced junction solar cell and method of fabrication

Abstract: An induced junction solar cell is fabricated on a p-type silicon substrate by first diffusing a grid of criss-crossed current collecting n + stripes and thermally growing a thin SiO 2 film, and then, using silicon-rich chemical vapor deposition (CVD), producing a layer of SiO 2 having inherent defects, such as silicon interstices, which function as deep traps for spontaneous positive charges. Ion implantation increases the stable positive charge distribution for a greater inversion layer in the p-type silicon near the surface. After etching through the oxide, to parallel collecting stripes, a pattern of metal is produced consisting of a set of contact stripes over the exposed collecting stripes and a diamond shaped pattern which functions as a current collection bus. Then the reverse side is metallized.

Silicon oxide coated metal having improved corrosion resistance

Abstract: The present invention provides a process for preparing silicon oxide layers on a substrate, and particularly on metal, having improved corrosion-protective properties. This is accomplished by making the silicon oxide protective layer hydrophobic, preferably by incorporating therein hydrophobic organosilicon residues. The protective layers are preferably prepared by vapor deposition in a vessel containing silicon and/or silicon oxides in the gasous form, oxygen, and a organosilicon compound containing at least one hydrophobic group bonded to the silicon.

Semiconductor electrodes. v. the application of chemically vapor deposited iron oxide films to photosensitized electrolysis

Abstract: The preparation of polycrystalline n-type Fe203 electrodes by the chemical vapor deposition (CVD) of iron oxide onto Ti and Pt substrates is reported. The behavior of these electrodes in aqueous solutions of different pH in the absence and presence of illumination is shown. Photoassisted electrolysis of water occurs at wavelengths longer than 400 nm and the current vs. wavelength curve for this process is compared to that of a CVD TiO2 electrode.

Synthesis and characterization of yttrium oxide (Y2O3) deposits

Abstract: The synthesis of yttrium oxide (Y2O3) was accomplished by evaporating elemental yttrium in the presence of oxygen. High‐rate physical vapor deposition was employed using both the reactive evaporation (RE) and activated reactive evaporation (ARE) processes. The ARE process resulted in a higher Y2O3/Y ratio for two reasons—more complete reaction and fewer globules of Y being ejected from the molten pool and landing on the deposit surface. The microstructure and mechanical properties of the deposit produced varied with the deposition temperature in accordance with the structural zone model of Movchan and Demchishin. Over a deposition temperature range of 121° to 721 °C, the surface energy, as determined by Hertzian fracture, varied from 645 erg/cm2 to 515 erg/cm2, and the microhardness varied from 320 kg/mm2 to 502 kg/mm2.