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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 7497-7505 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mechanisms underlying the refractive index changes in germanosilica films deposited by hollow cathode plasma enhanced chemical vapor deposition and subjected to UV irradiation are proposed based on observed changes in film thickness, stress, and structure. An increase in refractive index after UV exposure is observed in films deposited under low ion bombardment conditions. This increase in refractive index is accompanied by a reduction in film thickness which is an order of magnitude larger than that expected from the Lorentz–Lorentz relation. This behavior is shown to result from: (i) a significant degree of porosity in the as-deposited material; (ii) oxygen deficiency of the as-deposited material. Upon UV irradiation, the porous structure is compacted, thus accounting for the large decrease in thickness, while the oxygen deficiency is reduced causing a decrease in the material polarizability and counteracting the effect of the thickness reduction. On the other hand, germanosilica deposited under high ion-bombardment conditions is of normal optical quality and exhibits a decrease in refractive index after exposure to UV. This refractive index reduction is shown to be the result of three processes: structural dilation and stress relief on one side; and an increase in material polarizability on the other, with structural dilation having the largest effect. Annealing of the exposed samples has shown that most of the polarizability increase is likely to be annealed out at 500 °C, while the refractive index change caused by structural dilation is stable up to 800 °C. Finally, it is shown that during plasma enhanced chemical vapor deposition, germanosilica is more prone to nucleation and columnar growth than pure silica and therefore a higher level of ion bombardment is required in the former case in order to obtain a high quality homogeneous material. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4377-4382 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The use of a low oxidation state Ti compound, cyclopentadienyl cycloheptatrienyl titanium, (C5H5) Ti(C7H7) (CPCHT), as a potential source for TiN and Ti in plasma enhanced chemical vapor deposition processes has been investigated. This precursor provides us with a new chemical vapor deposition route to TiN films that offer an interesting contrast to films deposited from Ti(IV) precursors. Film depositions were carried out by introducing CPCHT, with H2 carrier gas, into the downstream region of a NH3, N2, H2, or mixed H2/N2 plasma. Low resistivity (100–250 μΩ cm) nitrogen-rich TiN films with little carbon or oxygen incorporation and good conformality were deposited with activated N2 or NH3 at deposition temperatures of 300–600 °C, inclusive. Mixed H2/N2 plasmas resulted in more stoichiometric TiN films with similar properties. The most striking feature of these films is the absence of columnar grain growth, in contrast to TiN films deposited using TiCl4 or Ti(NR2)4. Although the film texture was influenced by the plasma gas, the average grain size of the films deposited using activated N2 and NH3 was similar. The TiN films that we deposited were effective diffusion barriers between aluminum and silicon up to 575 °C. Depositions using activated H2 resulted in films with significantly less carbon than CPCHT, but still having a minimum of 2.7:1 C:Ti. The lower oxidation state of the precursor did not facilitate the deposition of a Ti-rich film. No depositions were observed with any of the reactant gases in the absence of plasma activation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 4148-4158 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a calculation of the structure and the optical transitions of sodium atoms and dimers embedded in argon clusters and matrices. We studied several different systems: A single sodium atom in a dodecahedral argon cluster, a Na atom in a substitutional site of a fcc (face-centered-cubic) Ar lattice containing 63 atoms and a sodium dimer in a 9-atom vacancy of the same fcc lattice (Na2@Ar54). For optimizing the system geometry in its ground state, we use a simplified tight-binding scheme of a metal cluster dressed by the metal-matrix and matrix-matrix van der Waals interactions. A procedure closer to ab initio methodology is then applied using e-Na+ and e-Ar semi-local pseudopotentials and core-polarization operators to determine the electronic structure of the metal valence electrons in the environment of the rare-gas atoms. The electronic transitions and oscillator strengths are obtained by a full two-electron configuration interaction (CI) treatment in the case of Na2@Ar54. The A1Σu+→X1Σg+ transition is redshifted in comparison to the free Na2 dimer. This phenomenon does not appear in the case of a matrix-isolated atom, where all lines are blueshifted. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6587-6591 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this study, with the use of a sensitive optical technique, we demonstrate the possibility of measuring the depth distribution of damage in GaAs that is generated by various ion-assisted processes such as ion implantation and ion assisted plasma etching. We have used this technique to measure the depth distribution of damage in both He and Ar implanted GaAs and in inert gas and reactive ion etched GaAs. The sensitivity of the technique allowed us to measure damage profiles over a large range of ion energies and ion doses. We have also confirmed previously published results indicating that damage created by sputter etching is inversely proportional to the mass of the ions used in the etching process.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1838-1841 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the effect of plasma excitation frequency on the properties of plasma-enhanced chemical vapor deposition silicon nitride films. The use of two radio-frequency sources, one at 270 kHz and the other at 13.56 MHz, enabled us to vary film properties such as stress by altering the amount of power supplied by each source. The low-frequency excitation was seen to favor the formation of N—H bonds in the deposited film. The relative amounts of N—H and Si—H bonds in the film were found to determine many of the film properties such as stress, conduction and wet etch rate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2589-2592 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-pressure metalorganic chemical vapor deposition (MOCVD) of aluminum using triethylamine alane (TEAA) is reported. This liquid source combines the chemical advantages of adduct precursors such as solid trimethylamine alane (TMAA), with the processing and handling advantages of liquid precursors such as triisobutyl aluminum (TIBA). High-purity Al films were deposited on TiN and thin in situ evaporated Cu and Ti films, which serve as activators for nucleation of Al. The electrical resistivities of the Al films on TiN were close to the 3 μΩ cm of sputtered Al. In the case of depositions on Cu, the Cu diffuses readily into the Al and serves to improve the electromigration resistance of the latter. The Al deposition rates using TEAA are 2–4 times those using TIBA at 250 °C, although the TEAA process is not fully optimized at this point and further work is needed to improve the film morphologies.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4820-4824 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Focused ion beam stimulated deposition of aluminum from trimethylamine alane, a white solid, and triethylamine alane, a colorless liquid, is reported. Initiation of growth on Si and SiO2 substrates is enhanced by in situ sputter cleaning of the surface with the Ga+ beam prior to introduction of the metallo-organic. Alternatively gas phase chemical activation with a silane coupling agent can enhance nucleation. Uniform nucleation on Al surfaces does not require any pretreatment. The Al features are electrically conducting, but incorporation of C and N from the amines leads to a resistivity approximately 300 times that of bulk Al. A qualitative model is presented that describes the balance condition for net material deposition as opposed to sputtering in terms of precursor flux and sticking probability as well as ion beam current density and beam scanning parameters. Film morphology and composition are also discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4135-4136 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solar cells with less than 1% front-surface metal shading loss have been made with a deep-grooving hollow cathode dry etching process. Compared with standard laser-grooved cells, a 4% relative increase in short-circuit current density has been demonstrated. Open-circuit voltages of over 640 mV (air mass 1.5, 25 °C), a fill factor of almost 79%, and the application of an antireflection coating have resulted in a one-sun efficiency of 19.2%. This is one of the highest efficiencies yet reported for a cleaved 4 cm2 silicon solar cell.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4152-4152 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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