Showing papers on "Substrate (electronics) published in 1970"

Optical second harmonic generation in form of coherent cerenkov radiation from a thin‐film waveguide

Abstract: We report optical second harmonic generation in form of coherent Cerenkov radiation. The fundamental wave at 1.06 μm propagates in a thin‐film optical waveguide which is simply a ZnS film vacuum‐deposited on a single‐crystal ZnO substrate. The nonlinear polarization excited in the substrate has a phase velocity exceeding that of radiation propagating freely in the substrate material. It thus acts as the source of the observed Cerenkov radiation.

Behavior of Cesium Oxide as a Low Work‐Function Coating

Abstract: A detailed picture of the behavior of cesium oxide as a low work‐function coating on III‐V semiconductors and on silver has been obtained. Measurement of required cesium and oxygen exposure for optimum photoyield shows that the compound normally formed is close to CS2O, with variations in required exposure for very thin and very thick layers. By making simultaneous Kelvin work‐function, photoyield‐threshold, and thickness measurements, it was possible to establish that the CS2O, an n‐type semiconductor, forms a heterojunction or Schottky barrier with its substrate. This provides a band bending which produces a gradual lowering of the vacuum level with increasing thickness to an ultimate work function of 0.6 eV. The photoyield and dark current from the substrate are limited by the interfacial barrier at the heterojunction. This barrier is 1.00±0.05 eV for a silver substrate and 1.23±0.03 eV for GaSb. The band‐bending distance in the CS2O is about 50 A and the hot electron scattering distance is 9 A. These data have been used in an improved calculation of the maximum Γ escape probability and requisite CS2O thickness for electron emission from III‐V semiconductors of different bandgaps. Electron emission from CS2O induced by an oxygen overpressure was also measured. CSOH is compared with CS2O as a work‐function lowering coating.

A System for Determining the Mass and Energy of Particles Incident on a Substrate in a Planar Diode Sputtering System

Abstract: A bakable ultrahigh vacuum system has been constructed to sample the particle flux incident on the substrate of a planar diode sputtering system. A beam of particles from the discharge is extracted into a long mean free path environment where it passes through a 90° deflection electrostatic analyzer into a quadrupole residual gas analyzer. The mass spectra of positive ions incident on a substrate during dc sputtering of copper and aluminum bronze are shown and the influence of hydrogen contamination is illustrated. The energy distribution of the Ar+ ions is presented for several values of the substrate bias.

QUANTUM YIELD OF GaAs SEMITRANSPARENT PHOTOCATHODE

Abstract: The quantum yield of a semiconductor thin‐film photocathode, operating in the transmission mode, has been derived from the continuity equation and light multiple reflections within the film and the substrate. The fit between experiment and theory is good for hv<1.7 eV. The differences between experiment and theory are explained in terms of the nonuniform population of defect states within the film. Electron diffusion lengths are found to be 0.3μ for the 1×1019 Zn‐doped 2.5‐μ ‐thick film and 0.1μ for the 3×1019 Zn‐doped 0.85‐μ ‐thick film, respectively.

The mechanism of polytype formation in vapour-phase grown ZnS crystals

Abstract: Morphological, x-ray crystallographic and x-ray topographic studies on many specimens grown in this laboratory lead to a consistent description of polytypism in vapour-phase grown ZnS. Crystal growth begins with the emerging of hexagonal 2H needles from the polycrystalline substrate. The needles thicken during the growth and often expand into platelets. The growth of the needles takes place around a screw dislocation with a Burgers vector 2nc D, where C 0 is the interlayer distance along the c axis. Consequently the (00.1) layers form a set of interleaved helical surfaces. Usually n= 1, but occasionally n> 1 and in this case subsequent formation of a poly-type is possible. This takes place by means of stacking faults which are introduced while the specimens are cooling down in the growth tube. Guided by the helical topology the stacking faults expand onto many equidistant (00.1) layers and thus transform the structure. It is demonstrated that all known features of ZnS polytypes in vapour-phase gr...

Control of RF sputtered film properties through substrate tuning

Abstract: A means has been found to control the rf potential of the substrate during rf sputtering. The application of this technique to the deposition of silica films has been investigatedin detail. The technique can be described as the use of an adjustable rf impedance between the substrate holder and ground electrodes, which generates an rf potential by virtue of the flow of rf current through it. Adjustment of the rf potential of the substrate results in a controlled dc bias potential developed at the film surface, which correlates directly with the physical properties of the deposited films. In general, the most desirable film properties are obtained when the dc substrate bias (obtained by adjusting the substrate-holder rf impedance) is at a high negative potential. The effect of substrate bias on etch rate, pinhole breakup thickness, and argon content has been measured.

Preparation of Thin BaTiO3 Films by dc Diode Sputtering

Abstract: Direct current diode sputtering of reduced BaTiO3 ceramic has been applied to the preparation of thin BaTiO3 films. Sputtering was carried out over a range of apparent sputtering rates of ∼500–1200 mg/Ah in atmospheres of argon and air. As the substrate, Pt sheet and fused quartz were principally used. Grain size of the deposited film was ∼1000 A for the Pt substrate at 400°C. The lattice constants were in good agreement with those of ordinary BaTiO3 when the Pt substrate was kept at a temperature above 1000°C, although they were slightly larger for substrates below 900°C. Measurements of optical density and observations of electron micrographs indicated that the sputter‐deposited films have more favorable properties of transparency, uniformity, and crystallization than vacuum‐evaporated films. The film prepared on a Pt substrate at 1000°C in an air atmosphere had a dielectric constant of 1700 and dissipation factor of 1.8% without post‐deposition treatment. However, the remanent polarization was very sma...

Epitaxial Growth of Gallium Phosphide on Cleaved and Polished (111) Calcium Fluoride

Abstract: The mechanism of growth of GaP on a cleaved CaF2 (111) surface was studied in situ in a high‐energy reflection electron diffraction system. It was found that in the early stages of growth, GaP forms tetrahedral nuclei with {111} faces. The three edges of the tetrahedron are parallel to the three 〈110〉 directions. These microcrystals coalesce and form a smooth film after a mean thickness of more than 300 monolayers of GaP is deposited on the surface. Temperatures for epitaxial growth of a single crystal without twinning as a function of the atom arrival rate were studied for GaP on a clean CaF2 surface and on a GaP‐covered CaF2 surface. It was found that growing GaP without twinning on a bare cleaved CaF2 surface requires a temperature ∼65°C higher than on a surface that is covered with GaP. The structural characteristics of the GaP film as a function of the substrate temperature are also discussed.

Method of fabrication of semiconductor device package

Abstract: Method of electrically interconnecting two electrical components, e.g. a semiconductor chip and a substrate, via contacts formed of aluminum, gold or silver by joining the contacts with a body of metal containing germanium and the same metal from which the contacts are formed, and heating the body of metal to the melting temperature of the eutectic alloy formed between germanium and the alloy.

Ellipsometric Technique for Obtaining Substrate Optical Constants

Abstract: A method for determining substrate optical constants, surface film thickness, and surface film optical constants has been devised by measuring the ellipsometer angles Δ and ψ at several angles of incidence. This method, previously reported as impossible, solves in a simple fashion the ellipsometry equations for one consistent values of surface film thickness in association with compatible values of substrate optical constants. The technique is advantageous in that vacuum ellipsometry is eliminated and previously unmeasured materials such as alloy structures may be studied readily. Data on aluminum, molybdenum, and silicon are presented illustrating the technique.

Semiconductor having tin oxide layer and substrate

Abstract: A semiconductor composite having a rectifying characteristic is provided by depositing a tin oxide film on a semiconductor substrate. In view of the fact that the tin oxide film has high transparency and conductivity the composite can be used as an excellent photoelectric device. Preferably the tin oxide film is deposited on the substrate by reacting a halogenated organic tin compound with oxygen at an elevated temperature. Conductivity of the tin oxide film can be enhanced by incorporation of a small amount of antimony trichloride into the dimethyl tin dichloride. It was found that there are preferred reaction temperatures, time periods, and amount of mixed antimony trichloride for providing a composite having the desired characteristics. By depositing a plurality of separate tin oxide films on a single substrate by a photo-etching process of tin oxide film an integrated photoelectric apparatus is provided.

Semiconductor photosensitive device with a rare earth oxide compound forming a rectifying junction

Abstract: A semiconductor device comprising a substrate made of semiconductor materials such as silicon, germanium and compounds of the elements of Groups III-V, and at least one layer defining at least one junction therewith, said layer being made of a mixture of a rare earth element and titanium oxide and/or zirconium oxide.

Glass-polysilicon dielectric isolation

Abstract: A COMPOSITE SUBSTRATE AND METHOD FOR MAKING DIELECTRICALLY ISOLATED DIFFUSED SEMICONDUCTOR DEVICES IS DISCLOSED. ISLANDS OF MONOCRYSTALLINE SILICON ARE FORMED IN ONE FACE OF THE SUBSTRATE. THE ISLANDS ARE NESTED IN A THIN POLYCRYSTALLINE SILICON LAYER WHICH IS BONDED TO A LAPPED MONOCRYSTALLINE SILICON WAFER BY AN INTERJACENT LAYER OF GLASS. THE GLASS HAS A HIGH SOFTENING POINT TEMERPATURE AND THERMAL EXPANSION PROPERTIES SIMILAR TO MONOCRYSTALLINE SILCON. D R A W I N G

Preparation and properties of lead-tin telluride photodiodes

Abstract: Monocrystalline epitaxial layers of PbxSn1−xTe (0·81 < x < 0·85) have been produced for use as photovoltaic devices capable of radiation detection in the 8–14 μm atmospheric window. The material was grown in an open tube, vapour phase transport system which produced layers of the required composition on lead telluride substrates. The crystalline quality and composition were checked by X-ray and electron diffraction techniques and found to be dependent on the substrate temperature. p-type layers of a reasonable quality, typically 100 μm thick, have been grown on {100} substrates. Photodiodes were fabricated using a diffusion technique which formed an n-type surface by stoichiometric adjustment. The electrical and optical properties of the photodiode were measured at 77°K and Dλp∗ values of up to 4 × 109cm Hz12W−1 at 10·6 μm for zero bias resistances of 10 Ω have been obtained.

Cutting tool with alloy coated sharpened edge

Abstract: A protective layer of an alloy of platinum and chromium is formed on a substrate by sputtering, this metal alloy providing a hard, corrosion resistant, protective layer for the substrate.

Electrical Characteristics of the Silicon Nitride‐Gallium Arsenide Interface

Abstract: The results of an investigation of the electrical characteristics of the silicon nitride‐gallium arsenide interface as determined by capacitance‐voltage (C‐V) curves is presented and discussed. The was pyrolytically deposited from and in the range 650°–750°C on n‐ and p‐type, , . A hysteresis of the C‐V curve is noted; the amount of curve shift is shown to be heavily process dependent. Times involved in curve shift both with and without applied bias are given. Surface state density for the best p sample is in the 1012 range.

End point detection method and apparatus for sputter etching

Abstract: The end point in sputter-etching metal layers, for example, from substrates is determined by employing a silicon, quartz, or the like, monitor control wafer in the sputter-etching environment which wafer has been previously coated with said metal, for example, in the same run as that used to fabricate the workpiece substrate. Thus, the monitor control wafer exhibits the same thickness of metal, or the like, as the thickness of the metal layer to be selectively sputter-etched from the substrate. The temperature exhibited by the monitor control wafer during the sputter-etching material removal process in monitored by an infrared radiation thermometer, by way of a quartz window. When the layer of metal, or the like, has been removed from the monitor control wafer, the temperature, as sensed by the infrared radiation thermometer during sputter-etching, declines thereby indicating the end point in the removal process of the metal layer, or the like.

Electrical and Photovoltaic Properties of CdS-Si Junctions

Abstract: CdS-pSi and CdS-nSi junctions are prepared by vacuum evaporation of CdS on Si crystals, and their electrical and photovoltaic properties are studied. The junction prepared on hot Si substrate (substrate temperature; 150°–250°C) has properties of hetero-junction, while the one on cold substrate (50°–80°C) shows properties resembling those of Schottky barrier. CdS-pSi junctions are generally superior to CdS–nSi junctions in rectifying properties. CdS–pSi cell on cold substrate shows excellent photovoltaic effect which is comparable to that of Si solar cell. The maximum solar conversion efficiency of CdS-pSi cells is about 5.5%. Here, the CdS layer is supposed to act as a semi-transparent electrode.

Method of preparation of lead sulfide pn junction diodes

Abstract: Flat, uniform planar diodes of PbS are prepared by either (1) epitaxially growing an n-type layer onto a p-type layer by depositing one layer epitaxially onto the other in a vacuum of at least 5 x 10 5 Torr wherein the substrate is at a temperature between 200-350 DEG C and the material to be deposited is at a temperature not lower than its sublimation point or (2) epitaxially growing a p-type layer on an n-type layer using the procedure described in (1) with the addition of vapors of a doping agent such as S, Se or Te, in the system. This method may also be applied to the closely related compounds PbxSn1-xSe and PbxSn1-xTe where x varies from 0 to 1 inclusive, hereinafter referred to as the lead-tin salt alloys.

MOS and vertical junction device characteristics of epitaxial silicon on low aluminum-rich spinel☆

Abstract: Various devices have been fabricated using silicon films grown epitaxially on low aluminum-rich spinel substrates. The insulating substrate provides complete isolation of the semiconductor devices and eliminates the parasitic capacitances of the back-biased p−n junctions. The low aluminum-rich spinel offers the advantages of better thermal stability and easier surface preparation for silicon epitaxy over both the conventional high aluminum-rich (MgO:3Al2O3) and the stoichiometric (MgO:Al2O3) materials. MOS capacitors, MOS transistors, and vertical junction diodes were constructed and studied using films with mobilities equal to or near the bulk values. Information on MOS capacitance vs. bias behavior, transistor characteristics, diode junction properties, and minority carrier lifetime was obtained. The silicon-spinel composites were also characterized by physical methods, and the nature of the defect structures was examined.

Integrated circuit process utilizing orientation dependent silicon etch

Abstract: Orientation-dependent etching is employed in the fabrication of a monolithic semiconductor circuit network to provide electrical isolation and increased packing density, while minimizing collector series resistance and output capacitance. Collector contact to a transistor component is made by the direct metallization of a buried low-resistivity substrate region exposed by the preferential etching operation.

Semiconductor doping compositions

Abstract: The disclosure herein relates to semiconductor doping compositions and to methods for their preparation and use. More particularly, the disclosure relates to liquid silica-based doping compositions which may be applied to a surface of a semiconductor substrate and, upon heating, an impurity is diffused from a film of the doping composition into the substrate to form a region therein having the desired electrical properties.

Method of selective chemical vapor deposition

Abstract: METALS ARE CAUSED TO BE DEPOSITED SELECTIVELY IN THE HYDROGEN REDUCTION OF THEIR COMPOUNDS WHICH ARE EITHER GASEOUS BEARING OR OF ADEQUATE VAPOR PRESSURE. THE PROCESS IS TERMED SELECTIVE-CHEMICAL VAPOR DEPOSITION SINCE THE METAL IS DEPOSITED ONLY ON PREPATTERNED AREAS OF A SUBSTRATE. THE SUBSTRATE IS SUITABLY A GLASS SUCH AS A BOROSILICATE, BOROALUMINO-SILICATE, PHOSPHOALUMINOSILICATE, PHOSPHOSILICATE OR SODA-LIME GLASS. THE SELECTIVECHEMICAL VAPOR DEPOSTION PROCESS OCCURS WHEN TWO SURFACES WITH DIFFERENT CHEMICAL REACTIVITIES ARE EXPOSED TO THE CHEMICAL VAPOR DEPOSITION ENVIRONMENT. THE PREPATTERNED AREAS PROVIDE ONE OF THESE SURFACES, SUCH AREAS COMPRISING A NUCLEATION LAYER OF A MATERIAL SUCH AS CHROMIUM, TUNGSTEN, MOLYBDENUM, COPPER, ALUMINUM, SILICON, SILICON DIOXIDE, ALUMINUM OXIDE, SILICON NITTRIDE AND THE LIKE, OR A COMPOSITE LAYER OF CHROMIUM-COPPER, CHROMIUM-COPPER CHROMIUM AND THE LIKE. THE OTHER SURFACE IS PROVIDED BY THE REMAINDER OF THE SURFACE OF THE EXPOSED SUBSTRATE. THE SURFACE PROVIDED BY THE PREPATTERNED AREA ACTS AS A METAL MUCLEATION SITE WHILE THE GLASS SURFACE IS CHEMICALLY ERODED (ABLATED) AND THE METAL DOES NOT NUCLEATE THEREON. AN EXAMPLE OF THE PROCESS IS THE CHEMICAL REDUCTION OF COPPER HEXAFLUOROACETYLACETONATE BY HYDROGEN IN THE PRESENCE OF HYDROGEN FLUORIDE OR SULFUR HEXAFLUORIDE IN A REACTION CHAMBER. THE CHAMBER CONTAINS A SUBSTRATE HAVING A PATTERNED NUCLEATING LAYER THEREON ON WHICH THE REDUCED COPPER DEPOSITS WHILE THE SUBSTRATE IS ABLATED BY THE FLUORIDE. THE DEPOSITION REACTIONS AND SIMULTANEOUS ABLATION REACTION, ACTING IN CLOSE PROXIMITY, ARE ESSENTIAL ELEMENTS OF THE INVENTIVES PROCESS.

The role of the substrate surface layer in the process of epitaxy part II. substrate structure and formation of epitaxial films

Abstract: A model is presented which explains semi-quantitatively the role of the substrate surface in the epitaxy of vacuum-deposited f.c.c. metal films on alkali halide substrates. The concept of critical accommodation centres is introduced. With the aid of the model the relative nucleation densities as well as the orientations of the nuclei in the initial stages of film growth are predicted for common substrate overgrowth combinations under a variety of growth conditions. The predictions seem to be in general agreement with experimental results.

Multilayered iii-v photocathode having a transition layer and a high quality active layer

Abstract: A thin III-V photoemitter crystal having a thickness ranging from 1 micron to 5 microns as grown on a III-V substrate. The bandgap was determined in advance by proportioning the constituents of the crystal causing the peak of the response curve to occur at a predetermined energy and absorb incident photons of the desired wavelength. Due to the high quality of the crystal, the electron diffusion length thereof was comparable to the thickness allowing transmission optics to be employed. Lattice mismatch between the active crystal and the base was minimized by a transition layer, or a progression of transition layers, of intermediate composition. The presence of this strain relieving structure permitted the growth of the thin, high quality single crystals having a relatively long electron diffusion length. As a specific example, a 20 micron transition layer of GaAs.90Sb.10 was epitaxially grown on a GaAs substrate. A three micron active layer of GaAs.85Sb.15 was grown over the transition layers. This composition of the active layer exhibited a bandgap energy of 1.17 ev corresponding to an absorption wavelength of 1.06 microns.