Showing papers on "Thin film published in 1973"

Optical and photoelectric properties and colour centres in thin films of tungsten oxide

Abstract: Thin films of Wo3 deposited on quartz substrates at room temperature have been shown to be amorphous in structure. The optical absorption spectra of the amorphous and crystalline films have been measured in the temperature range 110° to 500°K. The fundamental absorption edge of an amorphous film occurs at 3800 A which on crystallization moves to 4500 A. On the high-energy side of the absorption edge several absorption peaks are resolvable in both types of film. The frequency dependence of the absorption coefficient below 104 cm−1 is described by an expression of the form K (v, T) = K 0 exp[− (β/kT) (E 0 − hv)] and above 104 cm−1 it follows a square law dependency. The temperature coefficient of the band edges was found to be − 5.0 × 10−4 eV/°K and the estimated band gaps at 0°K were found to be 3.65 and 3.27 eV for the amorphous and crystalline films, respectively. The electrical conductivity of a thin film has been measured in the temperature range 298–573°K and the activation energy was found t...

Electrical conduction in concentrated disordered transition metal alloys

Abstract: Results are presented of an investigation on the origin of the low temperature coefficient of resistance in NiCr thin films. It is shown that this low temperature coefficient is an intrinsic property of the alloy. Besides NiCr a large number of disordered alloys containing transition metals have similar conduction properties, both in bulk and as a thin film. For these materials a correlation has been found between the resistivity and its temperature coefficient. These anomalous conduction properties are probably caused by the very small electron mean free path in these materials.

Phase Transition, Stability, and Depolarization Field in Ferroelectric Thin Films

Abstract: It is shown that the polarization in a thin ferroelectric film, which is sandwiched between semiconducting electrodes, is compensated incompletely The associated depolarization fields are size dependent and change the magnitude of the polarization, transition temperature, coercive field, and the order of the phase transition Thermodynamic considerations give stability requirements for thin films, which are different from the bulk The properties of a thin ferroelectric film, which in bulk form exhibits a second-order phase transition, are investigated as a function of thickness, temperature, biasing potential, and electrode properties Numerical results are presented for triglycinesulfate

Chemical Vapor Deposition of Thin‐Film Platinum

Abstract: Chemical vapor deposition of platinum for microelectronic applications has been studied with the aim of avoiding the radiation damage to dielectrics caused by sputter or e‐gun deposition. Two known CVD methods—the pyrolysis of Pt acetylacetonate and the reduction of —were tried and judged unsatisfactory for either purity or adherence. A novel method of Pt deposition using the trifluorophosphine complex is reported. The process is simple and reliable, and produces adherent bright films of crystals on a variety of substrates at 200°–300°C in 1 atm hydrogen. The Pt contains small amounts of residual phosphorus, mostly concentrated at the surface. Resistivity of 750Aa films is 1.8 times that of bulk Pt. MOS capacitors with CVD Pt field plates on both and alone have shown good stability under bias‐temperature aging. CVD Pt and Si interdiffuse readily to form ohmic or Schottky diode contacts.

High molecular weight, thin film piezoelectric transducers

Abstract: A transducer for converting electrical energy into mechanical or acoustic energy or vice versa using a converting means made of a thin film of high molecular weight polymer piezo-electric organic compound having orientated molecules and having electrodes bonded or deposited onto both surfaces thereof. When an electric current is applied to the electrodes, the thin film is extended or contracted in a direction different from the direction of orientation of the molecules. when the angle between these two directions is 45*, the extent of the extension or contraction of the thin film is at a maximum and the best converting efficiency can be obtained.

Reaction kinetics of tungsten thin films on silicon (100) surfaces

Abstract: The rate of reaction between Si (100) surfaces and tungsten films deposited by rf diode sputtering depends on the preparation of the silicon surface. If rf substrate bias is used to clean the silicon, then the rate of reaction in the temperature range 700–850 °C is independent of time, with an activation energy of 3 eV/mole W. The native oxide layer between the silicon and tungsten, that exists when sputter cleaning is not used, can act as a barrier to WSi2 formation. In this case, the time‐independent region is preceded by a period when the reaction rate increases with time. The rate is then controlled by two‐dimensional spreading of discontinuous WSi2 regions that originate at sites where the reaction barrier can be penetrated. After a continuous WSi2 layer is formed, additional growth can produce a stage where the increased path length for silicon diffusion causes the transport step to control the over‐all rate of the reaction. Quantitative models are presented for each of the three stages in the reaction. The models explain some of the macroscopic observations made on reacted layers.

Superconducting properties, electrical resistivities, and structure of NbN thin films

Abstract: Superconducting properties and electrical resistivities of NbN thin films have been studied as a function of sputtering parameters, film structure, and composition. A good correlation exists between superconducting Tc's and film structure and composition regardless of the sputtering conditions used to achieve this structure. The most important parameters affecting Tc are lattice parameter, crystal structure, island structure, and impurity content. Substrate temperature, Ar/N2 ratio, and impurity content are the principal sputtering parameters affecting film structure, and thus Tc.

Method of depositing thin film utilizing a lift-off mask

Abstract: A method for use in depositing thin films in the fabrication of integrated circuits which avoids edge tearing of the films. The method involves depositing a non-photosensitive organic polymeric material on a substrate, and forming on said polymeric layer a masking layer of an inorganic material, preferably metal, having openings in a selected pattern. Then, forming, by reactive sputter etching, utilizing the metallic mask as a barrier, openings through the polymeric layer extending to the substrate, the openings in the polymeric layer being aligned with and laterally wider than the corresponding openings in the metallic masking layer. The thin film to be deposited is then applied over the structure; it is, thereby, deposited on the substrate in said openings. Then, the remaining polymeric layer is removed, lifting off the masking layer and the thin film above the polymeric layer to leave thin film deposited in a selected pattern in the openings.

Note on the Anisotropy of the Conductivity in Thin Amorphous Films

Abstract: We present a new interpretation of the anisotropy of the conductivity in thin films of amorphous Ge and Si. The interpretation is based on a transition from percolation conduction to Miller and Abrahams's conduction at small film thickness. A simple theory, together with experimental data, is presented. The comparison between them is found to be good.

Acousto‐optical light diffraction in thin films

Abstract: The diffraction of optical guided waves in thin films through an acousto‐optic effect is treated. The diffraction of the bounded optical waves in thin films is a rather complicated phenomenon as compared with that of the free waves in bulk media. An expression for the diffraction efficiency has been derived using coupled‐wave equations. Acousto‐optical figure of merit and the mode coupling factor applicable to the diffraction in thin films are defined. The TE0 and TM0 waves in an As2S3 film deposited onto a LiNbO3 substrate were diffracted by Rayleigh waves with 93 and 72% efficiency at electrical input powers of 150 and 50 mW, respectively. The present experiment revealed that approximately 5% of the total acoustic power penetrated into the film and took part in the diffraction.

Preparation and optical properties of single crystal thin films of bismuth substituted iron garnets for magneto-optic applications

Abstract: Single crystal thin films of Bi substituted iron garnets have been grown by the liquid phase epitaxy technique. The growth conditions and compositions are presented together with the segregation coefficients of Bi and Pb as a function of growth temperature. The Faraday rotation and optical absorption have been measured for wavelengths between 0.7 and 0.46 μm. The superior magneto-optic properties (Faraday rotations of up to ten times larger than that observed for Y3Fe5O12) make these epitaxial layers attractive for magneto-optic devices. The influence of Pb incorporation on the optical properties of the films is discussed. Compositions of Bi and Ga(Al) substituted Gd3Fe5O12, which exhibit a magnetic compensation temperature near room temperature and high Faraday rotation, have also been prepared. The magnetic switching behaviour as a function of temperature has been determined. It shows that these films are especially suited for thermomagnetic recording using an argon ion laser at a wavelength of 5145 A.

Selective Area Metallization by Electron-Beam Controlled Direct Metallic Deposition

Abstract: Direct metallic deposition exploits the advantages of electron-beam exposure for the production of fine structures and avoids the use of resists and chemical etching. The process involves the electron-induced decomposition of metallic compounds in areas precisely defined by an electron probe. In principle, the resistivity of the deposits formed by direct metallic deposition can be controlled by regulating the amount of molecular dissociation which takes place. To date, in experiments with silver chloride, deposits with submicron dimensions have been obtained. Typical sheet-resistance values of the deposits range from 10 to 1000 Ω/square for exposures varied from 3×10−2 to 5×10−3 C/cm2. A Monte Carlo simulation of electron scattering in thin films on a supporting substrate has shown that the minimum deposit dimensions which can be expected from the process vary directly with film thickness and inversely with accelerating voltage. Experimental evidence is in agreement with the theoretical predictions.

X‐Ray Determination of Stresses in Thin Films and Substrates by Automatic Bragg Angle Control

Abstract: A modification of a scanning x‐ray topographic camera is described which automatically plots the lattice curvature of single crystal substrates strained by thin films or surface treatments such as diffusion and ion implantation. Film and substrate stresses are calculated from the radius of curvature. The unit operates as an electromechanical feedback system which maintains the orientation of a wafer such that the diffracted x‐ray intensity remains within preset limits while a finely collimated x‐ray beam traverses the wafer. An x‐y recorder continuously plots the changes in orientation as a function of position yielding a trace whose slope is proportional to the radius of curvature of the substrate lattice. The sensitivity of the apparatus is such that radii of curvature of 2000 m can be measured. In addition, the lateral spatial resolution is such that the local substrate lattice curvature can be determined under alternating and overlapping 2.5 mm wide stripes of metal and oxide films. It is also shown t...

Reactively evaporated films of scandia and yttria.

Abstract: Sc(2)O(3) and Y(2)O(3) films were prepared by evaporation from resistance heated boats in a residual gas atmosphere of oxygen. Films of much lower absorptance were obtained than from coatings produced in high vacuum. The short wavelength limit of high transparency was between 300 nm and 400 nm, while the long wavelength absorption edge was reached at about 11 microm. Refractive indices of 1.8-2.0 were measured for both oxides. The influence of annealing on the optical- properties of the films was investigated. The films were amorphous and proved to be mechanically very stable and water resistant. Electron micrographs showed smooth and uniform surfaces. By antireflection coatings of yttria the transmittance of silicon was increased from 52% to 99.4% at the maximum. Possible advantages by the application of Sc(2)O(3) and Y(2)O(3) instead of SiO for antireflection coatings on GaAs laser surfaces are discussed.

Polarization Instability in Thin Ferroelectric Films

Abstract: An experimental study of critical phenomena in thin ferroelectric films is presented which, for the first time, conclusively demonstrates that the polarization in thin films is drastically reduced as a result of depolarization effects Other causes, like impurities, structural defects, and domain formation, which can lead to reduction of polarization, are ruled out

Ferroelectric memory device

Abstract: A ferroelectric memory device utilizing the remanent polarization of a thin, ferroelectric film to control the surface conductivity of a bulk semiconductor and perform the memory function. The structure of the device is similar to a conventional MIS field effect transistor with the exception that the gate insulating layer is replaced by a thin film of active ferroelectric material comprising a reversably polarizable dielectric exhibiting hysteresis.

Optical waveguiding devices using monocrystalline materials of the sillenite family of bismuth oxides

Abstract: Monocrystalline materials of the sillenite family of bismuth oxides are used in the fabrication of optical thin-film devices. The sillenite materials are cubic in crystalline structure, transparent in the visible and near-infrared portions of the spectrum, electro-optic, piezoelectric, optically active, have useful acoustic surface wave coefficients and can be grown into high quality optical thin films by heteroepitaxial growth techniques. This wide range of properties in the light-guiding monocrystalline film should prove useful in the fabrication of a variety of thin-film devices suitable for integrated optical circuit arrangements. One such device is disclosed employing a thin light-guiding sillenite film upon which is deposited a pair of interdigital electrodes. The device serves as a thin-film electro-optical switch and modulator for a guided light beam.