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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 4446-4451 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rates and products of reaction are reported for the thermal energy charge transfer of Ar+ and Ar+2 with N2, H2, Xe, and Kr using a selected ion flow tube (SIFT). New rate coefficients were measured for the reactions Ar++Xe→Xe++Ar, Ar+2+N2 →Ar+⋅N2+Ar, Ar+2+H2 →ArH++H+Ar, and Ar+2+H2 →ArH+2+Ar; the rates are 4.3×10−13, 2.2×10−10, 3.6×10−10, and 1.1×10−10 cm3/s, respectively. The finding of (Ar⋅N2)+ as the product of the reaction of Ar+2 with N2 shows the bond energy of Ar+⋅N2≥1.27 eV in agreement with other techniques. In the case of H2, two reaction products are observed for reaction with Ar+2@B: ArH+ (85±10%) and ArH+2, but not Ar2H+ as suggested by earlier studies. Lower limits for the proton affinity of Ar (3.69 eV) and the dissociation energy for H+2⋅Ar (0.97 eV) are determined from the present work. Considering all the reaction rates, the proximity of the recombination energy of Ar+ and Ar+2 to a band in the photoelectron spectrum of a specific neutral reactant offers an explanation for the observed ordering of the relative rates of the monomer and dimer reactions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1630-1636 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rate coefficients for the reactions of Ar+ and Ar+2 with CH4 and CS2 are obtained as a function of energy by using a selected ion flow tube with an electric drift field (SIFT-DRIFT). A diagnostic analysis of the system and technique has been completed and allows rate coefficients to be reported with a high level of confidence. Rate coefficients and product branching ratios are determined for the methane reactions from thermal (room temperature) to center-of-mass kinetic energies of about 0.15 eV and for the carbon disulfide reactions from thermal to about 0.6 eV. The overall rate coefficients for these reactions do not vary a great deal over the investigated energy range. The greatest dependence is found for the slowest reaction Ar+ with CS2, where a minimum in the rate coefficient is observed near 0.15 eV. The behavior of the branching ratios for S+ and CS+2 suggests curve crossings between a repulsive state and the A, B, and C electronic states of CS+2.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1688-1690 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the growth and characterization of ultraviolet GaN quantum well light emitting diodes. The room-temperature electroluminescence emission was peaked at 353.6 nm with a narrow linewidth of 5.8 nm. In the simple planar devices, without any efforts to improve light extraction efficiency, an output power of 13 μW at 20 mA was measured, limited in the present design by absorption in the GaN cap layer and buffer layer. Pulsed electroluminescence data demonstrate that the output power does not saturate up to current densities approaching 9 kA/cm2. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 91 (1987), S. 2556-2562 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 92 (1988), S. 4947-4951 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an experimental study of ion fluxes, energy distributions, and angular distributions inside surface features on radio frequency-biased wafers in high-density, inductively driven discharges in argon. Specifically, we present data on ion distributions at the bottom of 100-μm-square, 400-μm-deep "holes" in the wafer. Transmission of ions to the bottom of the holes increases with increasing ion energy and decreases as the sheath size becomes comparable to the hole size. Ion energy distributions at the bottom of the holes are narrower than distributions on the flat wafer surface. The flux of ions remains normal to the wafer surface over most of the hole area but the flux of ions within 6 μm of the wall is angled towards the wall. The observed trends are consistent with effects expected due to bowing of the plasma sheath around the surface features on the wafer. Scattering of ions off sidewalls contributes at most, only a small part of the ion flux reaching the bottom of the hole. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2702-2704 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A GaN/AlGaN heterojunction bipolar transistor structure with Mg doping in the base and Si doping in the emitter and collector regions was grown by metalorganic chemical vapor deposition on c-axis Al2O3. Secondary ion mass spectrometry measurements showed no increase in the O concentration (2–3×1018 cm−3) in the AlGaN emitter and fairly low levels of C (∼4–5×1017 cm−3) throughout the structure. Due to the nonohmic behavior of the base contact at room temperature, the current gain of large area (∼90 μm diameter) devices was 〈3. Increasing the device operating temperature led to higher ionization fractions of the Mg acceptors in the base, and current gains of ∼10 were obtained at 300 °C. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1119-1121 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Inductively coupled plasma (ICP) etch rates for GaN are reported as a function of plasma pressure, plasma chemistry, rf power, and ICP power. Using a Cl2/H2/Ar plasma chemistry, GaN etch rates as high as 6875 A(ring)/min are reported. The GaN surface morphology remains smooth over a wide range of plasma conditions as quantified using atomic force microscopy. Several etch conditions yield highly anisotropic profiles with smooth sidewalls. These results have direct application to the fabrication of group-III nitride etched laser facets. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1119-1121 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal AlN grown on Al2O3 is found to be wet etched by AZ400K photoresist developer solution, in which the active component is KOH. The etching is thermally activated with an activation energy of 15.5±0.4 kcal mol−1, and the etch rate is found to be strongly dependent on the crystalline quality of the AlN. There was no dependence of etch rate on solution agitation or any crystallographic dependence noted, and the etching is selective over other binary group III nitrides (GaN, InN) and substrate materials such as Al2O3 and GaAs. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3705-3709 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron-cyclotron-resonance (ECR) and reactive ion etching (RIE) rates for GaN, AlN, InN, and InGaN were measured using the same reactor and plasma parameters in Cl2/Ar or CH4/H2/Ar plasmas. The etch rates of all four materials were found to be significantly faster for ECR relative to RIE conditions in both chemistries, indicating that a high ion density is an important factor in the etch. The ion density under ECR conditions is ∼3×1011 cm−3 as measured by microwave interferometry, compared to ∼2×109 cm−3 for RIE conditions, and optical emission intensities are at least an order of magnitude higher in the ECR discharges. It appears that the nitride etch rates are largely determined by the initial bond breaking that must precede etch product formation, since the etch products are as volatile as those of conventional III–V materials such as GaAs, but the etch rates are typically a factor of about 5 lower for the nitrides. Cl2/Ar plasmas were found to etch GaN, InN, and InGaN faster than CH4/H2/Ar under ECR conditions, while AlN was etched slightly faster in CH4/H2/Ar plasmas. The surface morphology of InN was found to be the most sensitive to changes in plasma parameters and was a strong function of both rf power and etch chemistry for ECR etching. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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