Showing papers on "Evaporation (deposition) published in 1975"

Molecular beam epitaxy of II‐VI compounds

Abstract: The II‐VI compounds are desirable for integrated optics due to their high electro‐optic coefficients, wide transparency range from the visible to beyond 10 μm, and the continuously adjustable refractive index offered by their ternary alloys. Films of waveguide thickness (1/2–2 μm) were grown here by evaporation, under ultrahigh vacuum, of the constituent elements (Zn, Cd, Se, Te) from separately liquid‐nitrogen‐shrouded graphite Knudsen cells onto temperature‐controlled chemomechanically polished single‐crystal substrates. A quartz‐crystal deposition monitor operating at the growth temperature was used in a novel way to determine the group‐VI/II impingement rate ratio which would produce stoichiometric films, by measuring deposition rate as a function of the impingement rate ratio. Dissociative reevaporation of growing films sets an upper limit to growth temperature; 1 μm/h reevaporation rates were calculated to be reached at 400 °C for CdTe, 470 °C for ZnTe and CdSe, and 570 °C for ZnSe. At impingement r...

Epitaxial growth of aluminum nitride films on sapphire by reactive evaporation

Abstract: Single−crystal films of AlN were fabricated on sapphire substrates by reactive evaporation of aluminum in ammonia gas. Films obtained have smooth and flat surfaces and there is no observed cracking. On the (0001) plane of sapphire, the c axis of AlN is aligned normal to the substrate surface, while on sapphire (0112), the c axis of AlN is inclined at about 28° to the film normal.

Cadmium sulfide solar cells

Abstract: Development, fabrication and applications of CdS solar cells are reviewed in detail. The suitability of CdS cells for large solar panels and microcircuitry, and their low cost, are emphasized. Developments are reviewed by manufacturer-developer. Vapor phase deposition of thin-film solar cells, doping and co-evaporation, sputtering, chemical spray, and sintered layers are reviewed, in addition to spray deposition, monograin layer structures, and silk screening. Formation of junctions by electroplating, evaporation, brushing, CuCl dip, and chemiplating are discussed, along with counterelectrode fabrication, VPD film structures, the Cu2S barrier layer, and various photovoltaic effects (contact photovoltage, light intensity variation, optical enhancement), and various other CdS topics.

Thin film formation of In2O3, TiN, and TaN by rf reactive ion plating

Abstract: In2O3, TiN, and TaN films were prepared on glass substrates by a rf ion‐plating technique. Indium, titanium, and tantalum were evaporated from evaporation sources in an oxygen or nitrogen atmosphere at a pressure on the order of 10−4 Torr. These films were observed to be pinhole free and uniform, showing excellent electrical and physical properties. The rf ion‐plating system appears to have some advantages over other methods of reactive deposition.

Properties of amorphous silicon films— Dependence on deposition conditions

Abstract: We report measurements on the electrical conductivity, optical absorption, electron spin resonance, Raman spectrum and electron diffraction of a set of a-Si films vaccum deposited at room temperature. As revealed by absorption at about 10 μm some of the films grown at deposition rates of about 0.4 A/sec contain considerable amounts of oxygen. All the properties, except Raman spectra and electron diffraction, are found to vary strongly with the deposition rate and the background pressure during evaporation. Qualitatively, these variations show significant correlations. For instance, if the electrical conductivity is higher so is the spin density, the optical absorption and the low-frequency refractive index. Also, increasing oxygen content leads to lower conductivity. In addition, we have tried to establish a rough quantitative relation between the shift in the optical gap and the change in the spin density by connecting each of these changes to the variation in the low-frequency refractive index. The temperature dependence of the electrical conductivity was also measured and it was found that below about 150 K the data are consistent with recent theoretical predictions, i.e., log σ exhibits a ( 1/T) 1 4 dependence.

Measurement of the neutral vapour density decay following the extinction of a high-current vacuum arc between copper electrodes

Abstract: The decay of neutral copper vapour density which follows the extinction of a high current (2-11 kA) vacuum arc between copper electrodes has been measured The results show that during the period 1-8 ms from current zero the vapour density decays at least an order of magnitude slower than expected on the assumption that vapour atoms generated by the arc move freely to the electrode and vacuum chamber surfaces where they condense The results can be explained, however, if it is assumed that the vapour is produced by evaporation from molten droplets which are emitted from the cathode spots

Solar cells and method for making same

Abstract: Solar cell elements are produced in accordance with the present invention in which a Cu2 S thin film is epitaxially formed on a CdS film by vacuum deposition in a heterojunction forming relationship. By a first method a Cu2 S layer on the order of 1/100 micron in thickness is formed on a CdS polycrystalline thin film by dipping in a solution of cuprous ions. The CdS film itself is less than 5 microns thick and rests on a conductive substrate. After the dipping step the Cu2 S film is increased to a thickness on the order of 1/10 micron by vapor evaporation of an additional amount of Cu2 S. By a second method both the CdS and Cu2 S are entirely vapor deposited on a substrate to achieve approximately the same final structure as the first method.

The observation of YbH2 produced by evaporation of ytterbium metal in a conventional vacuum coating unit

Abstract: When Yb was evaporated in a conventional vacuum-coating unit the thin films formed (≲ 200 A) contained orthorhombic YbH 2 , cubic Yb 2 O 3 and, possibly, normal face-centred cubic Yb and body-centred cubic Yb. The uncertainty with respect to the last two phases arises because these phases gave electron diffraction reflections which overlapped, within experimental error, reflections due to the first two phases. It was deduced that the amount of h.c.p. Yb in the films was small because the 10.0 and 10.2 reflections were not observed. In thick films (~1000 A) only f.c.c. Yb and a trace of YbH 2 were observed. The results are used to support the suggestion made by Gasgnier et al. [9] that f.c.c. phases previously attributed to thin films of Gd, Tb, Dy, Ho, Er and Tm are, in fact, due to the dihydrides of these metals.

Hall element and method of manufacturing same

Abstract: A cleaved surface of a crystal is used as a substrate for evaporation, and a high mobility semiconductor is evaporated to a thickness of 0.5 to 1.5 μm to form a deposited thin semiconductor film, on which a first magnetizable member having a high magnetic permeability is applied with an adhesive. Subsequently the substrate is removed, and an electrode is formed on the exposed surface of the evaporated thin film, and a second magnetizable member is applied thereon with an adhesive. Where a special humidity resistance is required, a reinforcing layer of an electrically insulating and moisture-impervious inorganic material is formed directly on the evaporated thin semiconductor film before the first magnetizable member is applied.

Vapor collimation in vacuum deposition of coatings

Abstract: An improved method is disclosed for coating substrates, such as turbine engine parts, at high rates by a physical vapor deposition process. The substrate to be coated and a vapor source, such as a metal alloy, heated by an electron beam, are placed in a chamber in which a gas pressure of greater than about 5 mT is maintained. When the source material is evaporated at a very high rate, such as greater than about 0.1 g/s or 13 g/s.m.sup. 2, the vapor is collimated and the collimation increases as the gas pressure or the evaporation rate increases. Collimation of the vapor allows a much higher deposition rate for a given evaporation power. Further, a much higher fraction of the evaporated material is deposited on the substrate. Despite the collimation, evaporated material deposits on areas of the substrate which are not in line-of-sight of the vapor source. If desired a substrate bias can be applied to bombard the substrate with ions before and during coating.

Selenium and selenium alloy evaporation technique

Abstract: A coating composition and method for vacuum coating inorganic photoconductive material onto a suitable substrate or backing through utilization of the compositions and irradiation heating devices.

Planar reactive evaporation method for the deposition of compound semiconducting films

Abstract: An apparatus and method for epitaxial film formation is disclosed. Planar reactive evaporation techniques suitable for scaling are employed to produce high purity compound semiconducting films at relatively low temperatures.

Laser‐induced evaporation of solid surfaces

Abstract: Atomic and ionic species evaporated by a CO2 laser pulse at power density up to 107 W/cm2 from surfaces have been studied by time‐resolved spectroscopy. The time‐of‐flight results for three emitting species from surfaces at different temperatures are consistent with a thermal model for evaporation.

Micromaterial coating method for substrate - operates without mask, using optically transparent material support

Abstract: The substrate is exposed at its back, non-coated side to an energy beam, so that the material on it is at least locally evaporated and condensed on the substrate to be coated, and placed near the front side of the device. The support for the material to be deposited is the base surface of a prism, or a similarly working surface; the substrate surface to be coated is place at a small distance (a few mu m) from the surface of the prism. An energy radiation, pref. a laser beam, is directed to the material to be evaporated pref. through an microscope so that after its evaporation practically the whole radiation is totally reflected from the now bare base surface area.

Optical constants of bulk and thin-film aluminum at 6328 Å

Abstract: The optical constants of bulk and thin-film aluminum were determined at 6328 A by use of ellipsometry. The samples were measured immersed in a liquid whose refractive index was within ± 0.02 of that of oxide films. In addition, the effect of the oxide film on the optical constants of evaporated aluminum was eliminated by making measurements at the metal–glass interface of a strain-free glass prism of known refractive index, and by making measurements in situ at pressures of 2 × 10−10 torr. Electropolishing of bulk polycrystalline and single-crystal aluminum yielded n’s ranging from 1.63 to 1.72 and k’s ranging from 7.56 to 7.77. The Drude model for 2.6 free electrons yields n = 1.55, k = 7.60; the Kramers–Kronig relationship yields n = 1.40, k = 7.50. In order to determine the effect of evaporation pressure on n and k, aluminum was evaporated at rates of 25 to 30 A/s onto optically polished fused silica at pressures of 1 × 10−5, 5 × 10−8, and 5 × 10−9 torr; the results were n = 1.70, k = 6.60; n = 1.62, k = 7.29, and n = 1.57, k = 7.52, respectively. The average values for aluminum evaporated at 1 × 10−9 torr of n and k that agree most closely with both the Drude and Kramers–Kronig relationship were 1.60 and 7.53, respectively. These values were used successfully to monitor the uniformity of samples used in all anodization experiments.

Some Magnetic Properties of Gd-(Fe, Co, Ni) Alloy Films Prepared by Co-Evaporation Techniques

Abstract: We have found that the co-evaporated film of Gd-Fe possesses a perpendicular easy axis anisotropy sufficient to cause the magnetization to be normal to the film plane. The critical thickness to obtain the perpendicular domain is about 500 A at the room temperature. However, both Gd-Co and Gd-Ni alloy films do not possess a perpendicular easy axis anisotropy in the thickness range from 0 to 1000 A.

Synthesis of dispersion‐strengthened alloys by the activated reactive evaporation process from a single rod‐fed electron beam source

Abstract: Oxide‐dispersion‐strengthened alloys have better high‐temperature properties but poorer low‐temperature strength compared to Ni‐base super alloys. Relative to these alloys, dispersion‐strengthened alloys of titanium carbide dispersed in a Ni‐base alloy matrix have been found to have good low‐ as well as high‐temperature strength. This investigation was concerned with the synthesis of dispersion‐strengthened alloys of TiC particles in a Ni matrix using the activated reactive evaporation (ARE) process. A Ni–Ti alloy rod was evaporated from an electron beam source in the presence of C2H2, all of the vapor species being activated or partially ionized using the ARE process. The deposits were characterized by x‐ray diffraction, electron microprobe analysis, microhardness, and transmission electron miscroscopy of carbon replicas. It was established that Ni–TiC dispersion‐strengthened alloys were produced by ARE process. The microhardness of the alloys decreased when annealed at high temperatures due to particle ...

The optical properties and stoichiometry of evaporated bismuth oxide thin films

Abstract: The optical properties of bismuth oxide thin films were measured for samples prepared by direct evaporation of Bi2O3. The as−evaporated low−rate (1−5 A/sec) films are microcrystalline, bismuth rich (relative to Bi2O3), and their optical absorption edge broadens and shifts to lower energies. High−rate (15−25 A/sec) films are amorphous and oxygen−rich with an absorption edge shifted to higher energies. Thermal decomposition of the Bi2O3 during evaporation causes these variations in film stoichiometry. We show that shifts in the absorption edge may be correlated directly with departures from stoichiometry. The refractive index and absorption edge change with thermal treatment in oxygen; the former varies linearly with the partial oxygen pressure over the range of pressures observed during evaporation in this study. The refractive index and extinction coefficient are compared with published data on Bi2O3 thin films. Using the Lorenz−Lorentz equation, the dependence of the refractive index on the bismuth/oxygen ratio is derived. Application to as−evaporated films shows a good correlation with our data.

Anomalous capacitance of Schottky barriers on strontium titanate

Abstract: An anomalous capacitance−vs−voltage characteristic of Schottky barriers on n−type single−crystal perovskite strontium titanate is described. This anomalous phenomenon is assigned to a heavily doped buried layer which forms during the evaporation of the metal contact.

Vacuum deposited epitaxial layers of PbSl−xSex for laser devices

Abstract: This paper describes an epitaxial vacuum deposition system used to grow heterostructure PbSl−xSex diode lasers that operated cw at 12K with threshold current densities as low as 60A/cm3. The relatively low temperature (300°C) growth process, which simulates closed tube vapor phase growth, minimizes substrate-epilayer strain and vacancy interdiffusion. Laser devices were fabricated by sequential evaporation of n-type and p-type PbSl−xSex layers onto PbSl−ySey substrates. n-type grown layers were sometimes found to have Pb-rich droplets on their surfaces, and a correlation has been made between the presence of these droplets and the starting source material.

Vacuum evaporation apparatus

Abstract: PURPOSE:To realize the simplification of apparatus, the improvement of working ratio and the stabilization of quality, by operating plural evaporation source with one evaporation electric source

Method for producing a magnetic recording medium

Abstract: An improved method of making a magnetic recording medium with excellent coercive force and rectangular ratio is provided by means of an ion plating technique. A support and an evaporation source of a magnetic Co-Si alloy are placed in an ion plating apparatus which is filled with an inert gas and kept at low vacuum. High voltage is then applied between the support and the evaporation source such that the former has a negative polarity and the latter a positive polarity, thereby causing a glow discharge zone in the apparatus. The magnetic alloy is evaporated into the glow discharge zone from the source to form a magnetic thin film on the support. Such a magnetic thin film can have a coercive force of 750 Oe or more and a rectangular ratio of 0.80 or more and can be used as a magnetic recording medium.

Vacuum evaporation of NaCl and KCl crystal surfaces doped with divalent impurities

Abstract: Thermal evaporation in vacuum from the surfaces of NaCl: Fe++; NaCl: Cd++; NaCl: Mn++ and KCl: Mn++ crystals has been studied. In all cases except that of cadmium, the impurity ions diffuse towards the surface and there produce nuclei of a second phase. These nuclei interact with the circular and rectangular step systems which are produced by evaporation and strongly modify the surface topography. The ratioV 〈110〉/V 〈100〉 of the perpendicular components of the step velocities has been measured as a function of heating time. On more prolonged heating the circular step structure is not stable, but becomes rectangular. This transition can be explained using the model proposed by Budke for vacuum evaporation.

Method of producing optical image on chromium or aluminum film with high-energy light beam

Abstract: A latent image is produced on a metallic film having at least one layer of chromium or aluminum by exposing the film to a light pattern. The intensity of the light from the light pattern must be below the threshold for evaporation of the metallic film. The latent image is developed by dipping the metallic film into an etchant.