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  • 1
    Electronic Resource
    Electronic Resource
    The adhesion of metallic films to laser-irradiated alumina (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5176-5179 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The adhesion strength of copper and nickel films deposited onto polycrystalline alumina (Al2O3) substrates is greatly increased by pulsed ultraviolet excimer (XeCl, 308 nm) laser irradiation of the alumina prior to metal-film deposition. Adhesion enhancement occurs for pulsed-laser energy densities, Ed, both below and above alumina's melting threshold (Edth∼0.7 J/cm2). Cross-section transmission electron micrographs of alumina irradiated at Ed(approximately-greater-than) Edth reveal an outer amorphous layer 40–60 nm thick that is formed during the rapid solidification process that follows pulsed-laser melting. Our results for gold, copper, and nickel films demonstrate that several factors contribute to metal-alumina bonding: (1) the chemical nature of the metal, as indicated by quite different adhesion strengths of sputter-deposited metals on unirradiated alumina substrates: 0.1 MPa for Au, 13 MPa for Cu, and 32 MPa for Ni; (2) the type and extent of laser-generated disorder/damage, since for gold significant bonding enhancement is obtained only if pulsed-laser melting of the alumina occurs; and (3) the irradiation atmosphere, as the adhesion strength of these metals to alumina is greatest if pulsed-laser irradiation is performed in an oxidizing atmosphere. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359264
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  • 2
    Electronic Resource
    Electronic Resource
    Laser ablation and column formation in silicon under oxygen-rich atmospheres (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3018-3020 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure formed at the surface of silicon by cumulative pulsed-laser irradiation in oxygen-rich atmospheres consists of an array of microcolumns surrounded by microcanyons and microholes. Formation of SiOx at the exposed surface of silicon is most likely responsible for the occurrence of etching/ablation that causes the continuous deepening of canyons and holes. The growth mechanism of columns that is supported by the experimental evidence presented here is a process in which the columns are fed at their tips by the silicon-rich ablation plasma produced during pulsed-laser irradiation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1324732
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructural evolution of laser-exposed silicon targets in SF6 atmospheres (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1629-1631 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructures formed at the surface of silicon during pulsed-laser irradiation in SF6-rich atmospheres consist of an array of microholes surrounded by microcones. It is shown that there is a dynamic interplay between the formation of microholes and microcones. Fluorine produced by the laser-induced decomposition of SF6 is most likely responsible for the etching/ablation process. It is proposed that silicon-rich molecules and clusters that form in and are ejected from the continually deepening microholes sustain the axial and lateral growth of the microcones. The laser-melted layer at the tip and sides of the cones efficiently collects the silicon-rich products formed upon ablation. The total and partial pressures of SF6 in the chamber play a major role in cone development, a clear indication that it is the laser-generated plasma that controls the growth of these cones. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1308538
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  • 4
    Electronic Resource
    Electronic Resource
    Silicon microcolumn arrays grown by nanosecond pulsed-excimer laser irradiation (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2322-2324 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Arrays of high aspect ratio silicon microcolumns that protrude well above the initial surface have been formed by cumulative nanosecond pulsed-excimer laser irradiation of silicon. Microcolumn growth is strongly affected by the gas environment, being enhanced in air or other oxygen-containing ambient. It is proposed that microcolumn growth occurs through a combination of pulsed-laser melting of the tips of the columns and deposition of silicon from the intense flux of silicon-rich vapor produced by ablation of the surface regions between columns. The molten tips of the columns are strongly preferred sites for deposition, resulting in a very high axial growth rate. The growth process is conceptually similar to the vapor–liquid–solid method used to grow silicon whiskers. However, in the present case the pulsed-laser radiation fulfills two roles almost simultaneously, viz., providing the flux of silicon-containing molecules and melting the tips of the columns. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123838
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  • 5
    Electronic Resource
    Electronic Resource
    Excimer laser ablation and activation of SiOx and SiOx-ceramic couples for electroless copper plating (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 3449-3451 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A XeCl (4.0 eV photon energy) pulsed excimer laser was used to study the ablation behavior of substoichiometric silicon oxide (SSO), SiOx with x∼1.0. The SSO ablation rate was quite high and its ablation threshold quite low (≤0.3 J/cm2), thereby making it an interesting material for pulsed laser patterning without the use of deep-UV radiation. Surface activation, as illustrated by subsequent copper deposition by the electroless process, was observed along well-defined narrow (∼10–20 μm) lines just beyond the edges of ablated trenches in SSO deposited on XeCl-transparent fused silica substrates. When a thin layer of SSO was deposited on polycrystalline Al2O3 or AlN substrates and subsequently laser treated, surface activation of these ceramics occurred on the laser-irradiated regions at much lower fluences and with fewer exposures than are required to activate the bare ceramic substrates. In both types of experiment, activation is believed to result from redeposition of elemental silicon, an ablation product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110116
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  • 6
    Electronic Resource
    Electronic Resource
    High-current superconducting Tl1Ba2Ca2Cu3Oy thick films on polycrystalline Ag by spin coating (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 294-296 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thick films of the high-temperature superconductor Tl1Ba2Ca2Cu3Oy with high current density Jc have been deposited on polycrystalline Ag substrates by a spin-coating method. The spin-coated precursor films were annealed in a two-zone Tl reaction furnace. Film thicknesses ranged from 10 to 30 μm, leading to good total current capabilities. The films have highly-textured c-orientation as evidenced by rocking curves with FWHM of 4° for the (006) peak. Scanning electron micrographs revealed a dense, plate-like layered structure and almost no reaction between the film and the Ag substrate. Values of Jc (77 K) up to 2.5×104 A/cm2 in zero field and more than 1000 A/cm2 in a 1 tesla field (H(parallel)c axis). © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114787
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  • 7
    Electronic Resource
    Electronic Resource
    Greatly improved adhesion of gold films sputter-deposited on laser-treated and thermally annealed alumina (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1065-1067 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects on adhesion strength of pulsed-laser irradiation prior to film deposition, and of thermal annealing following film deposition, have been studied for gold films deposited by ion beam sputtering on polished polycrystalline alumina (Al2O3) substrates. Three different atmospheres were employed for the laser irradiations: Ar-4% H2, air, and oxygen, all at 1 atmosphere pressure. A similar functional dependence of adhesion strength on laser energy density, Ed, was found for all of the gaseous environments: No change of adhesion strength for Ed≤0.5 J/cm2, maximum adhesion for Ed(equals sign)1.0–1.5 J/cm2, and decreased adhesion for higher Ed. A pronounced increase in gold-alumina adhesion strength was achieved when the alumina substrates were irradiated in an oxygen-rich atmosphere. A post-deposition 300 °C anneal doubled the adhesion strength to ∼50 MPa, approximately 500 times the strength of untreated gold-alumina couples. The adhesion strength initially increased rapidly with annealing time but saturated for times ≥ 1 hour. The adhesion enhancement can be attributed to the formation of a high-energy disordered alumina surface during rapid solidification following pulsed-laser melting of the near-surface region. This defective surface contains reactive sites where gold atoms can form strong bonds. The data show that these sites most effectively bond gold atoms when they are saturated with oxygen. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114231
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  • 8
    Electronic Resource
    Electronic Resource
    γ-Al2O3 formation from pulsed-laser irradiated sapphire (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2940-2942 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-resolution transmission electron microscopy was used to examine the effect of laser irradiation of sapphire (single crystalline α-Al2O3). It was observed that laser-melted material resolidified as γ-Al2O3 epitactically grown on the (0001) plane of α-Al2O3 having an orientation relationship (0001)α//(111)γ and [011¯0]α//[11¯0]γ. The interface between unmelted α-Al2O3 and resolidified γ-Al2O3 is atomically flat with steps of one to a few close-packed oxygen layers. The high thermal gradient in the α-Al2O3 did not produce any interfacial dislocations. However, pronounced lattice distortions existed in the resolidified γ-Al2O3. It is argued that the very rapid cooling rate present during solidification prevents the ordering of Al atoms that is required for the formation of the stable α-Al2O3 phase. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112960
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  • 9
    Electronic Resource
    Electronic Resource
    Smooth polycrystalline ceramic substrates with enhanced metal adhesion by pulsed excimer laser processing (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1791-1793 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Multishot pulsed XeCl (308 nm) excimer laser irradiation of commercial fine-grained polycrystalline alumina substrates is found to significantly improve their properties for metal film-bonding applications. A smoother surface finish is obtained, and the adhesion strength of subsequently deposited copper films to the laser-treated alumina surface is increased by a factor of 3–5 (200%–400%) under optimum laser conditions. Smoothing occurs when the alumina melts and undergoes molten flow before resolidifying. XPS measurements suggest that electrical activation of the near-surface region also may contribute to the enhanced copper adhesion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111810
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of sputter-deposited 316L stainless steel films (1992)
    Springer
    Journal of materials science 27 (1992), S. 5585-5590 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Sputter-deposited 316L stainless steel films deposited on various substrates were characterized using transmission electron microscopy and X-ray diffractometry. The deposits were found to be fine-grained and the phases present in the films depended on the nature of the substrate. Films of various thicknesses deposited on microscope slides or oxidized stainless steel substrates contained a mixture of two phases: a body centre cubic (b c c) and a modified hexagonal ε-phase. The hexagonal phase appeared to be an ordered phase, as suggested by the a O value of the structure, which is twice that for the ε-martensite found in many deformed stainless steels. These films were hard and brittle, as indicated by microhardness measurements. Films deposited on oxide-free austenitic stainless steel substrates, on the other hand, were mostly b c c and exhibited a dominant 〈2 00〉 texture. These films were softer and less brittle than those deposited on oxidized substrates. In situ high-temperature X-ray diffractometry revealed that the ε-phase transformed to b c c when the films were annealed at 773 K. On annealing at 873 K, the b c c phase transformed to face centre cubic, which remained stable on cooling to room temperature. These results agree with published data which suggest stability of the b c c phase up to 840 K. Some discrepancies from earlier published reports are discussed in the light of the present results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541627
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