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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 53 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The silicon integrated-circuits chip is built by contiguously embedding, butting, and overlaying structural elements of a large variety of materials of different elastic and thermal properties. Stress develops in the thermal cycling of the chip. Furthermore, many structural elements such as CVD (chemical vapor deposition) silicon nitride, silicon dioxide, polycrystalline silicon, etc., by virtue of their formation processes, exhibit intrinsic stresses. Large localized stresses are induced in the silicon substrate near the edges and corners of such structural elements. Oxidation of nonplanar silicon surfaces produces another kind of stress that can be very damaging, especially at low oxidation temperatures. Mismatch of atomic sizes between dopants and the silicon, and heteroepitaxy produce another class of strain that can lead to the formation of misfit dislocations. Here we review the achievements to date in understanding and modeling these diverse stress problems.
    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 69 (1991), S. 7901-7903 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An expression is derived for the critical thickness of heteroepitaxial films by taking the energy minimization approach. It is exactly identical to the critical thickness obtained by Matthew and Blakeslee [J. Cryst. Growth 27, 118 (1974)] using a force balance approach, after allowing for a discrepancy judged to be an unmentioned approximation in the latter. The equivalence of the two formulations is explained conceptually. The reason is pointed out for the very different critical thickness obtained by People and Bean [Appl. Phys. Lett. 47, 322 (1985); 49, 229 (1986)] using the energy minimization approach. It is further shown that misfit dislocations do not appear en masse catastrophically when the critical thickness is reached. Rather, their density increases gradually with the epitaxial thickness, approaching only asymptotically a value required for a complete relief of film stress as the thickness tends to infinity. Any observed sudden mass appearance of misfit dislocations must be attributed to a substantial supercritical thickness actually existing, prior to nucleation of dislocations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4009-4009 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: 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 69 (1991), S. 7892-7894 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Double heterostructure InGaAs-GaAs strained-layer single quantum well ridge waveguide lasers grown by molecular beam epitaxy were fabricated by using in situ laser monitored reactive ion etching to form the ridges. Continuous-wave threshold current as low as 3.5 mA was obtained on a ridge laser diode of 3.3 μm wide and 215 μm long having cleaved mirrors. The lasing wavelength is at 0.988 μm and the measured differential external quantum efficiency is 61%.
    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 76 (1994), S. 4479-4487 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We measured the increase in threshold currents due to lateral carrier diffusion in InGaAs/AlGaAs quantum-well ridge-waveguide laser diodes. The ridge stripes were fabricated by using both in situ monitored pure Cl2 reactive ion etching and selective wet etching to completely eliminate the spreading current in the conductive upper cladding layer while keeping the ridge sidewalls straight. After comparing the threshold data with a theoretical model, the ambipolar diffusion coefficient is found to be 22 cm2/s in the population-inverted InGaAs layer. This model is based on the calculated optical gain curve and the ambipolar carrier transport in the quantum-well and waveguiding layers. The dependence of carrier lifetime on the local carrier concentration is included in the calculation. Moreover, from another set of devices with the portions of the active layer outside the ridge stripes etched away, the surface recombination velocity is found to be around 1–2×105 cm/s.
    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 76 (1994), S. 3932-3934 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-efficiency and low-threshold InGaAs/AlGaAs quantum-well laser structures have been grown by molecular beam epitaxy. Material characterization was performed on polyimide-planarized ridge-waveguide lasers. The measured material gain data are compared to theoretical calculations that include the valence-band mixing effects. Total injection current densities of 84 and 60 A/cm2 have been measured from 50-μm-wide laser diodes with cavity lengths of 2850 μm (from a double-quantum-well sample) and 1770 μm (from a single-well sample), respectively. Moreover, we have also obtained a cw threshold current as low as 2.1 mA from a 1.7-μm-wide and 140-μm-long as-cleaved ridge-waveguide device. In addition, the lateral current leakage for the double-quantum-well sample is found to be twice that of the single-well one.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 783-785 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have analyzed and compared the resolved shear stresses of all 12 glide systems for the 60° dislocation for 〈110〉-aligned and 〈100〉-aligned isolation trenches. From among the 12 glide systems, we select for each trench alignment the one which exhibits the highest stress level. The results for the two alignments are then compared. We find that the largest resolved shear stress for a 〈110〉-oriented trench is about 30% more than that for a 〈100〉-oriented trench from both the isotropic and the anisotropic analyses. Other factors that may cause a reduction of dislocation density for the 〈100〉-trench alignment are also discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2685-2687 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We consider a model of stress-driven void growth in interconnection lines that are narrower than the metal grain size. The metal line is imbedded in an SiO2 matrix at a temperature T0, and incurs tensile stress after being brought down to an annealing temperature Tann. A void nucleates at a particular grain boundary, along which the diffusion is assumed to be so fast that the stress relaxation at that grain boundary is nearly complete in a very short time. This is assumed to occur before the void spans the width of the line. Thereafter, the void continues to grow by matter transport through bulk diffusion, cascading down sequential tiers of grain boundaries, resulting in a layer of extra matter at each grain boundary for strain relaxation. The kinetics of the void growth is given analytically. The consideration of climbing dislocations is deferred for future analysis.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 985-987 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bulk superconductivity was observed in the new system (InxPb0.75−xCu0.25)Sr2(Ca0.5Y0.5)Cu2 O7−δ. An increase in indium doping, 0≤x≤0.2, into the Pb sites results in an increase in the superconducting transition temperature Tc from 45 K for x=0 to 60 K for x=0.2. For nominal compositions x(approximately-greater-than)0.2, a decrease in Tc was observed, and an increase in the concentration of an impurity phase. From the results of the x-ray diffraction and energy- dispersive spectrometry, we identify the phase responsible for the superconductivity to be [In0.06(1)Pb0.69(1)Cu0.25]Sr1.99(7)[Ca0.47(1)Y 0.53(2)]Cu2O7−δ; this phase resulted from the synthesis of a sample of nominal composition (In0.2Pb0.55Cu0.25)Sr2(Ca0.5Y0.5)Cu2 O7−δ.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 987-989 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A GaAs-AlGaAs multiple-quantum-well structure was used as a substrate for overgrowth by a MgO buffer layer and superconducting YBa2Cu3O7−X thin film. The multiple quantum well serves as an in-depth probe for possible damage incurred by the semiconductor substrate due to the relatively high temperature and active oxygen environment that characterizes the superconductor growth. The thickness of the MgO buffer layer was varied and correlated with both the superconducting properties of the overlying YBa2Cu3O7−X and the quality of the substrate as determined by photoluminescence measurements of the multiple quantum wells. Both high quality superconducting YBa2Cu3O7−X and excellent photoluminescence spectra of the substrate were obtained with a MgO thickness of 450 A(ring) and quantum wells as close as 350 A(ring) to the surface.
    Type of Medium: Electronic Resource
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