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Showing papers on "Amorphous solid published in 1979"


Journal ArticleDOI
G. Lucovsky1
TL;DR: In this article, it was shown that the frequencies of the bond-stretching vibrations of Si-H groups in amorphous solids vary systematically with the electronegativities of the next nearest neighbor atoms of the network.

520 citations


Journal ArticleDOI
TL;DR: In this paper, an improved version of the Hesse-rubartsch method was applied to the evaluation of the hyperfine field distribution in an amorphous Fe79.5Si1.5B19 alloy at room temperature.
Abstract: An improved version of the Hesse-Rubartsch method is described. This method is applied, together with an adapted peak shape, to the evaluation of the hyperfine field distribution in an amorphous Fe79.5Si1.5B19 alloy at room temperature. The detailed structure of this distribution is discussed.

417 citations


Journal ArticleDOI
TL;DR: In this paper, the transition to single crystal of ion-implanted amorphous Si and Ge layers is described in terms of a liquid phase epitaxy occurring during pulsing-laser irradiation.
Abstract: The transition to single crystal of ion‐implanted amorphous Si and Ge layers is described in terms of a liquid‐phase epitaxy occurring during pulsing‐laser irradiation. A standard heat equations including laser light absorption was solved numerically to give the time evolution of temperature and melting as a function of the pulse energy density and its duration. The structure dependence of the absorption coefficient and the temperature dependence of the thermal conductivity were accounted for in the calculations. In this model the transition to single crystal occurs above a well‐defined threshold energy density at which the liquid layer wets the underlying single‐crystal substrate. Experiments were performed in ion‐implanted amorphous layers of thicknesses ranging between 500 and 9000 A. The energy densities of the Q‐switched ruby laser ranged between 0.2 and 3.5 J/cm2; time durations of 20 and 50 ns were used. The experimental data are in good agreement with the calculated values for the amorphous thickness–energy−density threshold. The model deals mainly with plausibility arguments and does not account for processes occuring in the near‐threshold region or below the melting temperature.

352 citations


Journal ArticleDOI
TL;DR: In this article, the orientation of overlayer films induced by artificial surface patterns was proposed as graphoepitaxy, which is a special case of graphopitaxy induced by surface patterns.
Abstract: Uniform crystallographic orientation of silicon films, 500 nm thick, has been achieved on amorphous fused‐silica substrates by laser crystallization of amorphous silicon deposited over surface‐relief gratings etched into the substrates. The gratings had a square‐wave cross section with a 3.8‐μm spatial period and a 100‐nm depth. The 〈100〉 directions in the silicon were parallel to the grating and perpendicular to the substrate plane. We propose that orientation of overlayer films induced by artificial surface patterns be called graphoepitaxy.

270 citations


Journal ArticleDOI
Helmut Kronmüller1, Manfred Fähnle1, M. Domann1, H. Grimm1, R. Grimm1, B. Gröger1 
TL;DR: A review of the current state of the research work on soft magnetic materials can be found in this article, where it is shown that the displacement of domain walls is described fairly well by the conventional potential theory developed previously for crystalline materials.

223 citations


Journal ArticleDOI
TL;DR: In this article, the structural origin of defects in amorphous silicon-hydrogen alloys is investigated based on voids that grow perpendicular to the film surface and are associated with coupled SiH2 units.
Abstract: The relationships between hydrogen vibrational spectra, electron spin densities and refractive index are investigated for a range of plasma-deposited amorphous silicon-hydrogen alloys. Results are also presented on the morphology of thick films as shown by scanning electron microscopy. A model is proposed for the structural origin of defects in these alloys based on voids that grow perpendicular to the film surface and are associated with coupled SiH2 units.

207 citations



Book ChapterDOI
01 Jan 1979
TL;DR: In this article, the authors present a unified approach to interpret the relaxations of amorphous polymers in a unified way, independent of the details of chemical structure, by use of the time-correlation function approach to partial and total relaxations.
Abstract: The article outlines our current understanding of the multiple relaxations observed in crystalline and amorphous solid polymers, as studied using dielectric techniques. An attempt is made to interpret the relaxations of amorphous polymers in a unified way, independent of the details of chemical structure, by use of the time-correlation function approach to partial and total relaxations. In addition, the recent studies of polymers of medium and high degrees of crystallinity are reviewed.

203 citations


Journal ArticleDOI
TL;DR: In this article, the kinetics of the electrochromic process and the stability with different WO3 electrodes (evaporated film, electrodes obtained by anodic oxidation of W, polycrystalline, and single crystal) were studied.
Abstract: The kinetics of the electrochromic process and the stability with different WO3 electrodes (evaporated film, electrodes obtained by anodic oxidation of W, polycrystalline, and single crystal) were studied. Cyclic voltammetry and chronoamperometr y, together with optical absorption measurements in the electrochromic region were carried out. Impedance measurements at different frequencies of the WO3-H2SO4 (aq) interface were also made to compare the evaporated film and anodic oxide electrodes. These measurements showed that the electrochromic reaction at the WO3 anodic film was much faster than that at the evaporated film electrode (by about two to three orders of magnitude). This difference in the reaction rates reflects the difference in the rate of diffusion of H + in the films. Infrared spectroscopic measurements of the films were carried out to obtain information about the water content of the films. The differences in the kinetic behavior of the electrochromic process at the two electrodes were attributed to differences in porosity and water content of these two films. The stability of the WO3 film toward dissolution in aqueous solution was also shown to depend on the quantity of water in the film. In addition electrochemical behavior in the electrochromic region was studied in several other systems, including systems which contain H~SO~ as the electrolyte but with nonaqueous solvents and systems which contain Li +, replacing H +, in nonaqueous solvents. The solvent and the cation both affect the kinetics of the electrochromic process and the stability of the amorphous films. The electrochromic process at single crystal and polycrystalline WO3 was also studied and compared to the behavior of the amorphous film electrodes.

197 citations


Journal ArticleDOI
TL;DR: Amorphous alloys based on silicon and containing hydrogen and fluorine have been fabricated using a radio-frequency glow discharge in silicon tetrafluoride and hydrogen as mentioned in this paper, and they have been well characterized using conductivity, photoconductivity, field-effect and infra-red techniques.
Abstract: Amorphous alloys based on silicon and containing hydrogen and fluorine have been fabricated using a radio-frequency glow discharge in silicon tetrafluoride and hydrogen. Films have been well characterized using conductivity, photoconductivity, field-effect and infra-red techniques. Amorphous alloys fabricated from a gas ratio of SiF4 : H2=10: 1 are shown to possess a localized density of states with a minimum value of less than 1017 cm−3 eV−1. These films are highly photoconductive, devoid of photostructural changes and are mechanically stable. Because of the low density of localized states, the alloys have been doped with 50 v.p.p.m. of arsine in the premix to attain a room temperature conductivity ≥ 5 Ω−1 cm−1.

183 citations


Journal ArticleDOI
TL;DR: In this paper, a number of continuous random lattices can be classified as specific one-to-one mappings of ordered lattices of spaces of constant curvature onto the usual 3-dimensional euclidean space.
Abstract: 2014 A number of continuous random lattices can be classified as specific one-to-one mappings of ordered lattices of spaces of constant curvature onto the usual 3-dimensional euclidean space. These mappings put emphasis on two types of lattice defects : surface defects for spaces of constant positive curvature (i.e. spherical spaces), disclinations for spaces of constant negative curvature (Lobatchewskian spaces). This method might provide clues for solving the difficulties encountered in the description of amorphous solids with metallic or covalent bonds. LE JOURNAL DE PHYSIQUE LETTRES TOME 40, 1 er NOVEMBRE 1979,

Journal ArticleDOI
TL;DR: In this article, the electrical properties of recrystallized amorphous silicon layers, formed by BF+2 implants or Si++B+ implants, have been studied by differential resistivity and Hall effect measurements.
Abstract: Electrical properties of recrystallized amorphous silicon layers, formed by BF+2 implants or Si++B+ implants, have been studied by differential resistivity and Hall‐effect measurements. Electrical carrier distribution profiles show that boron atoms inside the amorphized Si layers can be fully activated during recrystallization at 550 °C. The mobility is also recovered. However, the tail of the B distribution, located inside a damaged region near the original amorphous‐crystalline interface, remains inactive. This inactive tail has been observed for all samples implanted with BF+2. Only in a thicker amorphous layer, formed for example by Si+ predamage implants, can the entire B profile be activated. The etch rate of amorphous silicon in HF and the effect of fluorine on the recrystallization rate are also reported.

Journal ArticleDOI
TL;DR: In this paper, the authors described experiments on the coating of germanium targets on a water-cooled electrode in a butane r.f. plasma (13.56 MHz) with the electrode capacitively coupled to the supply to provide a negative bias to enhance ion impact.


Journal ArticleDOI
TL;DR: The great stability of the amorphous state of 1,2-propanediol is shown by the critical warming rates above which no crystallization occurs, as well as by the difficulty in crystallizing on cooling.

Journal ArticleDOI
01 Jan 1979-Polymer
TL;DR: In this article, it was established that the incorporation of an impact modifier altered the superstructure of the polypropylene matrix by decreasing the average size of spherulites through which the impact strength of the composite may be influenced.

Journal ArticleDOI
TL;DR: Amorphous silicon films prepared by radiofrequency plasma decomposition of silane contain between 10 and 25 at % hydrogen depending on the potential and temperature of the substrate and plasma parameters as discussed by the authors.

Patent
01 Nov 1979
TL;DR: In this paper, a pattern-forming process using a radiation sensitive chalcogenide layer composed of a laminate of amorphous and thin silver layers was described, and the pattern was left on the substrate according to a given pattern by the above process.
Abstract: This invention relates to a pattern-forming process using a radiation sensitive chalcogenide layer composed of a laminate of amorphous chalcogenide layer (2) and thin silver layer (3), and discloses a pattern-forming process characterized by etching out an amorphous chalcogenide layer (22) not doped with silver at an unexposed area under an irradiation of a light (6) or an accelerated corpuscular beam by a plasma etching with a fluorine-series gas and also a pattern-forming process wherein silver-doped amorphous chalcogenide layer (21) left on the substrate according to a given pattern by the above process is used as an etching mask and then the substrate layer (1c) is etched out by a plasma etching to form the given pattern on the substrate.

Journal ArticleDOI
TL;DR: In this article, the structure, sintering rates and chemical composition of 20 to 200-A-diameter Pt-O and Pd-O alloys were examined using scanning transmission electron microscopy and energy dispersive X-ray microanalysis.


Journal ArticleDOI
TL;DR: The optical constants of amorphous thin films of Sb2S3 prepared by vacuum evaporation were determined by means of transmission electron microscopy as discussed by the authors, and the optical constants in the amorphized films are rather structureless but on crystallization several structures are observed in e2 at energies of 1.88, 2.48, 3.86 and 5.25 eV.


Journal ArticleDOI
TL;DR: The magnetic properties and crystallization temperatures of alloys in the ternary Fe-B-Si system are reported in this paper, where the Curie temperature increases slightly on replacement of boron by silicon.
Abstract: The magnetic properties and crystallization temperatures of alloys in the ternary Fe-B-Si system are reported. The Curie temperature increases slightly on replacement of boron by silicon. This results in a sharp ridge of relatively constant room-temperature saturation magnetization extending from Fe 80 B 20 to Fe 82 B 12 Si 6 . The coercivity exhibits a broad minimum, both before and after stress relief annealing, in the region around Fe 81 B 15 Si 4 and extending at least to Fe 77 B 13 Si 10 . The crystallization temperature increases with increasing silicon and with decreasing iron and boron. The alloys with silicon are generally easier to prepare in the amorphous state than the binary Fe-B alloys. Thus for the highest saturation magnetization alloy combined with ease of preparation, stability, and lowest losses, the alloys between Fe 81 B 17 Si 2 and Fe 82 B 12 Si 6 are preferred.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that the crystalline quality of Si layers grown on sapphire substrate (SOS) by the CVD method can be greatly improved through the use of implantation of Si ions and subsequent thermal annealing at relatively low temperatures.
Abstract: We demonstrate that the crystalline quality of Si layers grown on sapphire substrate (SOS) by the CVD method can be greatly improved through the use of implantation of Si ions and subsequent thermal annealing at relatively low temperatures (∼550 °C). This method utilizes an amorphous layer created by ion implantation near the sapphire/Si interface. Subsequent regrowth of this amorphous layer starting from the relatively perfect Si surface region leads to a much improved Si crystalline layer, as evidenced by MeV 4He+ channeling and TEM measurements. When the implantation‐formed amorphous layer is located at the outer portion of the Si layer, thermal annealing leads to only a small reduction in the amount of defects in the regrown layer as compared to the unimplanted sample. In these layers, epitaxial regrowth occurs with the same rate and activation energy observed in self‐ion‐implanted 〈100〉 Si.


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that the superior solar absorptance of amorphous silicon can be utilized in photothermal solar energy converters of sufficient stability without sacrificing the advantages of CVD fabrication.


Journal ArticleDOI
TL;DR: In this paper, a systematic understanding of the heat distortion temperature (HDT) of amorphous and semi-crystalline polymers is possible through a direct correlation with the modulustemperature behavior.
Abstract: A systematic understanding of the heat distortion temperature (HDT) of amorphous and semi-crystalline polymers is possible through a direct correlation with the modulustemperature behavior. For amorphous polymers, the precipitous drop in modulus at the glass transition temperature makes the HDT a well-defined, reproducible and predictable property. Furthermore, the addition of reinforcing fillers has a negligible effect on the HDT of the amorphous polymer. For semi-crystalline polymers, however, the exact opposite may hold true. The modulus exhibits a “plateau” region between the glass transition and the melting transition. Hence the HDT often is difficult to predict, is sensitive to thermal history and may be greatly increased through the addition of fillers. More importantly, the HDT may not be an accurate measure of the upper use temperature for semi-crystalline polymers in load bearing situations since considerable stiffness may still be retained even upon exceeding the HDT.

Journal ArticleDOI
TL;DR: In this article, the transition behavior of polycarbonate and poly(ethylene terephthalate) blends was examined for their transition behavior by thermal analysis and dynamic mechanical testing, and it was concluded that PC and PET are completely miscible in the amorphous phase for PET-rich compositions.
Abstract: Melt blends of polycarbonate and poly(ethylene terephthalate) were prepared and examined for their transitional behavior by thermal analysis and dynamic mechanical testing. A single Tg was observed for compositions containing more than 60%–70% PET by weight while compositions below this range showed two glass transitions. From this it is concluded that PC and PET are completely miscible in the amorphous phase for PET-rich compositions, whereas PC-rich blends separate into two amorphous phases which apparently contain both components. Melting point and crystallization behavior are conssistent with these conclusions and suggest that very little if any interchange reactions occur between the ester and carbonate groups during melt mixing.

Journal ArticleDOI
TL;DR: In this paper, the hydrogen concentration and density of amorphous semiconducting films prepared by glow discharge decomposition of silane have been measured as a function of deposition temperature using inductively coupled as well as a capacitively coupled plasmadecomposition system.
Abstract: The hydrogen concentration and density of amorphous semiconducting films prepared by glow‐discharge decomposition of silane have been measured as a function of deposition temperature. An inductively coupled as well as a capacitively coupled plasma‐decomposition system was used. For samples prepared by the capacitively coupled system, the hydrogen content decreased from 26 to 8 at.% and the density increased from 1.9 to 2.27 g/cm3 as the substrate temperature was increased from 25 to 450 °C.