Showing papers on "Pulsed laser deposition published in 1974"

A new GaAs, GaP, and GaAsxP1−x vacuum deposition technique using arsine and phosphine gas

Abstract: A new vacuum deposition process for depositing thin films of GaAs, GaP, and GaAsxP1−x is described. This process is similar to the standard molecular beam technique except that the arsenic and phosphorus are supplied from the decomposition of arsine and phosphine gas. The advantages of this process over the more conventional one-source and two-source molecular beam techniques are that the new gas-source process is more easily controlled and more reproducible and the deposition source materials are essentially inexhaustible, permitting a large number of samples to be coated during a single run. The process has been optimized for depositing polycrystalline films 800–1000-A thick with sheet resistivities exceeding 1013 Ω/square for use as a resistive sea for silicon-diode-array camera tube targets. Variations in the deposition parameters, such as gallium temperature, the ratio of gallium to arsenic or phosphorus flux incident on the substrates, deposition time, and substrate temperature, were made to determi...

Chemically Vapor Deposited Polycrystalline-Silicon Films

Abstract: In recent years polycrystalline silicon deposited by chemical vapor deposition has become of importance in many semiconductor applications. The formation and properties of films deposited for different applications are reviewed in this paper, and the use of the films in semiconductor devices is discussed. The deposition temperature, gases, and impurities are found to have the major influence on the properties of the films. These deposition variables significantly affect the crystal

Superradiant emission at 5106, 5700, and 5782 Å in pulsed copper iodide discharges

Abstract: Superradiant laser emission at 5106, 5700, and 5782 A is reported from pulsed discharges in copper iodide vapor at temperatures near 600°C. This conclusion is supported by pulse shortening of the visible emission and a marked increase in the relative visible intensity compared to the copper resonance radiation as the critical temperature range is approached. Electrical dissociation of the copper iodide, electron impact excitation of the copper atoms, and radiation trapping of the 3248- and 3274-A resonance lines are proposed as the principal inversion mechanisms. Below \sim450\deg C, where insufficient copper iodide is vaporized to provide resonance trapping, the upper laser level lifetimes are ∼10 ns, whereas at higher temperatures trapping is complete and the effective2P 3/2 and2P 1/2 lifetimes are 615 and 370 ns, respectively. The reservoir temperature at which stimulated emission is observed is in good agreement with calculations of the threshold ground-state copper densities required for resonance trapping. These experiments indicate that practical copper laser systems operating at substantially reduced temperatures can be developed provided instabilities in the copper iodide discharges can be overcome.

Method of physical vapor deposition

Abstract: A method of physical vapor deposition is described wherein a source of evaporant material and a substrate are placed in a vacuum chamber maintained at a pressure of less than 10 4 Torr. A vapor of the evaporant material is produced for deposition on the substrate. The vapor is intercepted with the beam of electrons to produce positive ions, and the substrate is maintained at a negative electrical potential sufficient to cause substantial heating of the substrate by ion bombardment.

Intense electron-beam initiation of a high-energy hydrogen fluoride (HF) laser

Abstract: A superradiant hydrogen fluoride (HF) laser is described in which an intense electron beam, propagating in a SF 6 and C 2 H 6 mixture, is used to initiate chemical reactions that produce vibrationally excited HF molecules. The variation of laser energy as a function of SF 6 pressure for fixed composition and as a function of composition at a fixed SF 6 pressure has been investigated. These experimental parametric curves are discussed in terms of the relevant physics. The maximum laser energy of 228 J in a 55- ns full-width-at-half-maximum (FWHM) pulse was obtained with a mixture of400-torr SF 6 and 40-torr C 2 H 6 . Measured efficiency for converting deposited beam energy to laser energy propagating in the forward direction was as large as 8 percent.

Optical thin film coater

Abstract: Disclosed is an improved optical thin film coating system comprising all essential elements of resistive and electron beam evaporation systems, chemical vapor deposition systems and reactive plasma deposition systems. Sequences of cleaning and deposition processes which previously required moving substrates through several chambers are performed in a single vacuum chamber. The evaporative sources also efficiently vaporize solid materials to provide reactive gases for reactive plasma and chemical vapor deposition processes, which were previously difficult or impossible to perform. Substrate movement, masking, and monitoring means previously used with evaporative sources are used to control thickness and uniformity of films deposited by chemical vapor and reactive plasma processes, to provide optical quality films.

A New Method for Chemical Vapor Deposition of Silicon Dioxide

Abstract: Es wird uber eine neue Abscheidungsmethode von SiO2- Filmen aus der Dampfphase′ durch Oxidation von dampfformigen Alkylsilanen berichtet.

Method for producing single crystal films

Abstract: The reaction zone for the deposition of a metal oxide film on a crystal substrate inside a reaction chamber is shifted during a chemical vapor deposition process by the systematic control of the process parameters of the system.