Showing papers on "Evaporation (deposition) published in 1983"

Modified palladium metal‐oxide‐semiconductor structures with increased ammonia gas sensitivity

Abstract: It is known that palladium metal‐oxide‐semiconductor (Pd‐MOS) structures are sensitive detectors for hydrogen gas. We show that the evaporation of a thin film of catalytically active metals on top of the structure can increase the sensitivity towards ammonia considerably. It was found that the thin metal must be in contact with the oxide to cause the increased sensitivity. The largest increase was observed with the transition metals Ir and Pt. The ammonia sensitivity could be enhanced about 60 times compared to that of an unmodified structure

TeOx thin films for an optical disc memory

Abstract: Tellurium suboxide thin films TeOx were found to change in refractive index and extinction coefficient on thermal or optical heating, with accompanying changes in the reflectivity and transmission. The preparation method and thermal or optical properties of the TeOx thin films were investigated to obtain a stable and highly sensitive optical disc memory. A two‐source evaporation method using Te and TeO2 provided uniform and any desired composition. The properties of the film depended on the x value; increasing x to as large as x=1.2, which represents a Te‐poor composition, produced an excellent humidity and heat stability, and decreasing x to 0.8 made the film more sensitive to a laser diode, but susceptible to humidity. The TeO1.1 thin film was found to sufficiently satisfy all requirements for practical disc applications. A reflective optical disc was prepared using the TeO1.1 thin film deposited on a polymethylmethacrylate substrate with grooves for optical tracking. This disc is capable of recording v...

The Study of Metal Colloids Produced by Means of Gas Evaporation Technique. I. Preparation Method and Optical Properties in Ethanol

Abstract: Three new methods for the preparation of metal colloid in organic solvent are presented. These methods were the matrix isolation method, the gas flow-cold trap method and the gas flow–solution trap method; the latter was found to give a good colloid solution for the optical measurements. The metals reported are high purity Ag, Au, Cu, In, Al, Ca, Sn, and Pb. The stability of the colloid is dependent on the kind of metals: Al, In, Au, and Ag are stable, and Pb, Sn, Ca, and Cu are unstable. The optical absorption spectra of these sols were measured in ethanol solution in Ar atmosphere. They are discussed in relation to those reported on the solid matrix or on the solid substrate.

Highly oriented ZnO films grown by laser evaporation

Abstract: A relatively new deposition technique involving laser‐assisted evaporation is applied to the deposition of thin ZnO films. Highly oriented and crystalline films of ZnO were obtained by CO2 laser evaporation of ZnO powder targets on substrates held at 50–450 °C. Optical transmission spectra of these films show a sharp cutoff at 380 nm. The refractive index, as measured by ellipsometry, is 1.98–2.04. As‐grown films are conducting (0.1–1 Ω cm), but become insulating when 0.1% Li2O is added to the source. SAW devices built with these films proved the piezoelectric nature of laser‐evaporated ZnO. It is found that the laser deposition technique is applicable to producing device quality ZnO films with good reproducibility.

Electrochemical Properties of WO 3 · x ( H 2 O ) I . The Influences of Water Adsorption and Hydroxylation

Abstract: Electrochemcial properties of evaporated amorphous films on conductive glass substrates have been studied in organic electrolytes in order to clarify the influence of water in the films on electrochromism. Compositions of water in the film have been analyzed by using FT‐IR spectra and 1H‐NMR. We conclude that the water adsorbed in the film during the evaporation and from ambient air not only leads to a fast electrochromic reaction at first, but also reacts gradually with by hydroxylation and/or hydrolysis to shift the potential of the cathodic reaction to the negative side and that the hydroxylated film layer loses the electrochromic coloration density.

Epitaxial relations in group‐IIa fluoride/Si(111) heterostructures

Abstract: CaF2, SrF2, BaF2, and mixed (Ca,Sr)F2 films have been grown epitaxially on Si (111) substrates by vacuum evaporation The epitaxial relation between these fluoride films and the substrates has been investigated by ion channeling analysis Both the CaF2 and SrF2 films prefer to have orientations rotated 180° about the normal to the substrate surface In contrast, the vast majority of (Ca,Sr)F2 films have orientations identical to those of the substrate, and the BaF2 film is composed of a mixture of the two Analysis was also made on a Si/CaF2/Si(111) double heterostructure, which showed that the top Si film is again rotated 180° about the normal to the underlying CaF2 surface

Surface preparation effects on efficient indium‐tin‐oxide‐CdTe and CdS‐CdTe heterojunction solar cells

Abstract: The effects of CdTe surface preparation and subsequent junction formation have been investigated through characterization of ITO/CdTe and CdS/CdTe heterojunction solar cells formed by electron beam evaporation of indium‐tin‐oxide (ITO) and CdS onto single crystal p‐type CdTe. Surfaces investigated include air‐cleaved (110) surfaces, bromine‐in‐methanol etched (110) and (111) surfaces, and teh latter surfaces subjected to a hydrogen heat treatment. Both air‐cleaved and hydrogen heat treated surfaces have a stoichiometric Cd to Te ratio. The ITO/CdTe junction formation process involves an air heat treatment, which ahs serious effects on the behavior of junctions formed on these surfaces. Etched surfaces which have a large excesss of Te, are less affected by the junction formation process and result in ITO/CdTe heterojunctions with solar efficiencies of 9% (Vsc =20 mA/cm2). Use of low‐doped CdTe results in junctions characterized by considerably larger open‐circuit votages (Voc =0.81 V) which are attributabl...

Chemical Bath Deposition of Thin Film Cadmium Selenide for Photoelectrochemical Cells

Abstract: Chemical bath deposition provides an attractive, low cost method of producing cadmium chalcogenide thin films. Intimate contact between the bath solution and the substrate material permits uniform deposition on substrates of complex geometry, presently difficult with spray pyrolysis, vacuum evaporation, or electrodeposition techniques. For CdSe, rigorous control of deposition conditions promotes the formation of a hexagonal, specularly reflecting deposit rather than a less desirable sphalerite (cubic) powdery deposit. Scanning electron microscopy reveals a small grained layered plate morphology similar to that produced by the evaporation method. Specularly reflecting CdSe films can be formed over large area substrates at a thickness optimal for their use as photoelectrochemical cells (PEC). Employing polysulfide as the redox couple, conversion efficiencies as high as 6.8% have been achieved in the authors' laboratory for these films using a tungstenhalogen white light source.

Chemically induced enhancement of nucleation in noble metal deposition

Abstract: Organic disulfides, chemisorbed as monolayers on aluminum and silicon oxides, have been found to induce significant changes in the morphologies of thermally evaporated Au and Ag films for film thicknesses (mass average) up to 100–200 A. Measurements of the electrical conductivities as a function of film thickness show a marked shift of the onset of conduction to lower thickness for films deposited on treated substrates compared to films on untreated substrates. Transmission electron microscopy shows that the conductivities correlate qualitatively with sample morphology. In particular, films on treated substrates show metal clusters of higher densities which connect at lower coverages than do films on untreated substrates.

Active matrix substrate

Abstract: PURPOSE:To enable to manufacture the substrate for an active matrix panel at a low temperature and moreover by a simple process by a method wherein an Al layer or an Al alloy layer to be used as a low temperature impurity diffusion source is used for a wiring layer, and moreover for up to the gate electrode material. CONSTITUTION:A silicon thin film 21 is formed on the transparent substrate 20, and moreover after a gate insulating film 22 is formed and the gate electrode material 23 is deposited, the gate electrode 25 is formed by patterning, and a gate insulating film 24 is formed using the gate electrode thereof as the mask. Then the Al layer or the Al alloy layer 26 of Al-Si, etc., to be used both as the diffusion source and as the wiring layer is formed according to the evaporation method or the sputtering method, and after then by performing annealing at 300-450 deg.C for about 5-20min, Al diffuses in the Si film as impurities at a comparatively low temperature. As a result, source and drain diffusion layers 27, 28 and a channel 29 are formed, and after then the Al layer or the Al alloy layer used as the diffusion source is patterned to be utilized as it is as the wiring material for lead wires 30, 31 from the source and the drain, etc. Because the diffusion source is used as the wiring layer as it is, simplification of the process can be attained.

Bar evaporation source having improved wettability

Abstract: As intermetallic composite, bar evaporation source constructed from a mixture of borides and nitrides for use in the evaporation of metals, e.g., aluminum, is arc sprayed with a layer of the metal to be subsequently evaporated therefrom before use. The coated layer of the metal to be evaporated increases the wettability of the bar source cavity and creates greater electrical stability when compared with similar but uncoated bars.

Electrochromic display element

Abstract: PURPOSE:To form an oxidation coloring type electrochromic layer without coloring of the film itself in the stage of filming by using a composite material of an oxidation coloring type electrochromic material and a metallic oxide in constituting an oxidation coloring type electrochromic layer CONSTITUTION:Iridium oxide is used as an oxidation coloring type electrochromic material and tantalum pentoxide as a metallic oxide, and a film is formed from these materials by a reactive ion plating method An ion plating device has a pair of crucibles 12a, 12b, electron guns 13a, 13b for generating electron beams, a high frequency coil 14 and a holder 15 in a bell-jar 11 evacuated to a vacuum A substrate 18 formed by depositing by evaporation a transparent conductive material 17 on a glass plate 16 is fixed on the holder 15 in a way that the plate 16 faces the holder 5 Oxygen O2 is introduced as reactive gas into the bell-jar 11 An iridium metal 19 is installed as a vapor deposition source in the crucible 12a, and tantalum pentaoxide 20 is installed as a vapor deposition source in the crucible 12b The element having the electrochromic layer consisting of the composite oxide of tantalum pentaoxide and iridium is thus obtd

Evaporation arc stabilization

Abstract: Apparatus and method for evaporation arc stabilization including a target having a surface of material to be evaporated; circuitry for establishing an arc on the target surface for evaporating the target material, the arc being characterized by the presence of charged particles and a cathode spot which randomly migrates over the target surface; and a confinement ring contacting and surrounding the target surface, the ring being composed of a material such as boron nitride having (a) a secondary emission ratio less than one at the mean energies of the charged particles of the arc and (b) a surface energy less than that of the evaporated target material to thereby confine the cathode spot to the target surface. Further, the secondary emission ratio of the confinement ring is preferably less than that of the target.

Grain boundary phenomena in n‐type CdTe films grown by hot wall vacuum evaporation

Abstract: Films of n‐type CdTe doped by coevaporation of indium have been deposited by hot wall vacuum evaporation on 7059 Corning glass and BaF2 single crystal substrates. Layers deposited on glass show a dark resistivity of the order of 105 Ω cm and a light resistivity of 500 Ω cm under AM1.5; photoexcitation increases the electron density but does not affect the electron mobility. Layers deposited on BaF2 show a dark resistivity of about 3 Ω cm and a light resistivity of about 2 Ω cm, corresponding to an electron density of 3.9×1016 cm−3 and an electron mobility of 48 cm2/V s; illumination of these layers on BaF2 increases the electron mobility but not the electron density. A quantitative model for grain boundary transport in polycrystalline materials is shown to give good agreement with the experimental data.

Precision marking of layers

Abstract: Selective incision of metallic layers overlying semiconductors by laser ablation (evaporation) of selected regions of a dye sensitized coating on each such metallic layer, followed by etching of the metallic layer to avoid objectionable alloying by laser scribing of the metallic layer to provide the desired incisions.

Semiconducting behavior of Ag2Te thin films and the dependence of band gap on thickness

Abstract: Thin films of Ag2Te of various thicknesses in the range 500–1500 A have been prepared by thermal evaporation of the compound under vacuum on clean glass substrates held at room temperature. The electrical resistance of the films has been measured as a function of temperature during heating, which was carried out immediately after the film formation. The observed exponential decrease of resistance with temperature up to the transition point points to the semiconducting nature of the low temperature polymorph of Ag2Te. The band gap of the low temperature phase is calculated for various thicknesses of the films and it is found that the band gap is a function of film thickness, increasing with decreasing thickness. The increase in the band gap, which was found to be inversely proportional to the square of the film thickness, is attributed to quantization of electron momentum component normal to film plane.

Method and apparatus for making ohmic and/or Schottky barrier contacts to semiconductor substrates

Abstract: Disclosed is a method of making ohmic and/or Schottky barrier contacts to a silicon semiconductor substrate in which before depositing the metal on silicon semiconductor substrates containing integrated circuits which are covered by a mask having contact windows, the metal is initially deposited on freshly cleaned blank silicon semiconductor substrates mounted in the same vacuum chamber. In this manner any traces of oxygen present in the vacuum chamber are chemisorbed by the blank substrate resulting in deposition of a high quality oxide-free metal contacts on the device substrates. The disclosed apparatus comprises a deposition chamber maintained at a predetermined low pressure, a substrate holder carrying a plurality of blank silicon substrates and silicon substrates containing integrated circuit structures covered by a mask having contact windows, a source of metal placed in the chamber for evaporation or sputtering and a shutter arranged in close proximity with said substrate holder for shielding selected substrates during the initial stages of metal deposition.

Mechanism of Laser-Assisted Evaporation of II–VI Semiconductors

Abstract: The evaporation mechanism of CdTe, HgTe and HgO . 7CdO . 3Te under high power laser irradiation was investigated using mass spectroscopy. Results were compared to thermal evaporation. Thermal evaporation yields Te molecules and Cd(Hg) atoms. In the case of HgTe and Hgo . 7Cdo . 3Te, the evaporation is noncongruent. Evaporation induced by the irradiation of 1.06 μm Nd:YAG laser pulses evolves atomic Hg, Cd and Te congruently. The dissociative and congruent nature of this process makes it a very attractive technique for depositing thin films.

Film deposition equipment

Abstract: This film deposition equipment is arranged so that metal is evaporated in atmosphere including reactive gas introduced in a vacuum, and pressure variation of the reactive gas caused by the metal evaporation is detected to know and control metal evaporation amount.

XPS, ESR and resistivity measurements on amorphous silicon oxynitride films (a-SiOxNy) prepared by reactive evaporation of Si in presence of NO2

Abstract: Silicon oxynitride films (SiOxNy) are prepared by reactive, electron gun evaporation of Si at nitrogen dioxide pressures ranging from 10−6 T to 5 × 10−5 T. In this way the brightness of W-filament of the electron gun probably contributes to the photodissociation of NO2 and favours the introduction of oxygen. The oxygen composition, determined by XPS analysis, may be varied nearly over the entire range between Si and SiO2 (O < x < 2), that of the nitrogen remaining limited (y < 0.4) Starting from pure a-Si, with rising NO2 pressures and oxygen content, the resistivity and the optical transmission vary gradually — as for a-SiOx samples — to insulating and transparent samples. The XPS Si2p electron energy shift and the ESR g-value shift are also well connected with the composition and the local surroundings of the Si atoms. The behaviour of thse spectra versus the composition provides arguments for a description of the structure of the SiOxNy films with a ternary random bonding model and local bondings of the kind |Si-(Si4−X−YOXNY)| (X or Y = 0, 1, 2, 3, but Y is generally less than X, X + Y ⩽ 4). On the other hand the ESR spin density remains high (1018–1019 cm−3) if care is taken in its determination, and is not related to the conduction and the sample composition for high x values, but seems to be connected with the method of preparation.

Thermal and pulsed laser evaporation of single phase AsxP1−x alloys

Abstract: The atomic and molecular species evolved during thermal and pulsed laser evaporation of single phase AsxP1−x alloys have been examined using mass spectroscopy. Thermal evaporation yields tetratomic molecules of the form As4−nPn (n=0, 1, 2, 3, 4) as well as diatomic As2, P2, and AsP. Pulsed laser vaporization using a Q‐switched train of 1.06‐μ neodymium: yttrium aluminum garnet (Nd:YAG) pulses primarily evolves atomic As and P species, some fraction of which are ionized. The generation of atomic beams containing one or more of the group V elements from a homogeneous source of controllable stoichiometry has some potential applications for the growth of optoelectronic thin films.