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  • 1
    Electronic Resource
    Electronic Resource
    The interdiffusion of Si, P, and In at polysilicon/GaAs interfaces (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1845-1854 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gallium arsenide (GaAs) encapsulated at 450 °C with thin films of amorphous silicon has been annealed at temperatures up to 1050 °C and the resulting polysilicon (poly-Si)/GaAs interfaces investigated with secondary ion mass spectroscopy, Rutherford backscattering, and transmission electron microscopy. Little or no interdiffusion is detected at undoped Si/GaAs interfaces whereas Si diffuses from P- or As-doped Si to depths as great as 550 nm in the GaAs after 10 s at 1050 °C. The flux of Si into the GaAs is correlated with the flux of Ga and As into the Si and both increase with increases in the dopant concentration of the Si. The diffusion of other Si dopants into the GaAs, including P and In, is also detected. This enhanced diffusivity of Si, P, and In in GaAs results from the diffusion of point defects into the GaAs created by the diffusion of the Ga and As into the encapsulant. Numerical simulations using position-dependent impurity diffusion coefficients predict that Si, P, and In diffusivities in GaAs at doped poly-Si interfaces are enhanced by factors of 104 above their respective intrinsic bulk equilibrium diffusivities, where known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341760
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  • 2
    Electronic Resource
    Electronic Resource
    Asymmetries in dislocation densities, surface morphology, and strain of GaInAs/GaAs single heterolayers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4843-4852 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dislocation densities, surface morphology, and strain of Ga1−xInxAs/GaAs epitaxial interfaces as a function of indium composition and layer thickness have been investigated by transmission electron microscopy, medium energy ion blocking, and double-crystal x-ray diffractometry. The electron microscopy shows that in the thinnest dislocated films (90 and 160 nm, x=0.07) 60° α dislocations form first in one 〈110〉 direction at the interface. Surprisingly, however, an asymmetry in residual layer strain is not detected in these samples, suggesting that the dislocations have the same Burgers vector or are evenly distributed between two Burgers vectors. Orthogonal arrays of dislocations are observed in films thicker than 300 nm (60° and edge-type, x=0.07). In this case, dislocation densities in each 〈110〉 direction are equal to within experimental error while an asymmetry in in-plane strain is measured (18% and 30% for x=0.07, 300, and 580 nm thick, respectively). An unequal distribution of Burgers vectors of 60° or edge-type dislocations is considered responsible for the strain asymmetry in these thicker samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341232
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  • 3
    Electronic Resource
    Electronic Resource
    Acclimatizing micropropagated black cherry by comparison with half-sib seedlings (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Black cherry (Prunus serotina Ehrh.) plantlets were cultured in vitro, transferred to potting mixture and evaluated for 8 weeks for acclimatization to a varying, but controlled environment. Whole plantlet growth and water relations were monitored and compared to seedlings of comparable size of the same maternal genotype grown under different conditions, but given the same pretest environment. At one week ex vitro. gravimetrically determined leaf conductance of plantlets was high, but became closer to that of seedlings in both magnitude and diurnal pattern as acclimatization progressed. By 8 weeks, leaf conductance of plantlets was nearly identical to that of seedlings, but the xylem water potential of the plantlets was significantly less. Logarithmic regressions of shoot vs root dry weight indicated that seedlings were allocating twice as much dry matter to shoot than to root growth compared to 4- and 8-week plantlets. Over the same period, stomatal densities of both seedlings and plantlets decreased and stomatal pore lengths increased. Multiple adventitious roots of plantlets emerged from a single site just below the root collar whereas secondary or lateral roots of seedlings originated acropetally along the central root axis. Leaf conductance of plantlets at 8 weeks was similar to that of seedlings indicating satisfactory acclimatization. The larger relative root growth rate of plantlets compared to the shoot, however, was associated with lower stem xylem water potential. The anomaly may be a consequence of the method of in vitro root formation. Plantlet growth rates were lower than growth rates of seedlings and their leaf area was correspondingly less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb01344.x
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  • 4
    Electronic Resource
    Electronic Resource
    Planar Ge/Pd and alloyed Au-Ge-Ni ohmic contacts to n-AlxGa1−xAs (0≤x≤0.3) (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 721-723 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Specific contact resistivity ρc of planar Ge/Pd ohmic contacts to n-type AlxGa1−xAs is measured as a function of AlAs mole fraction x and anneal temperature Tann. The functional dependence of ρc on Tann is the same for all x, decreasing to a minimum at 275–325 °C. This indicates that the ohmic contact formation mechanism is independent of x(0≤x≤0.3) as verified by MeV Rutherford backscattering spectrometry and Read camera glancing angle x-ray diffraction. Decomposition of an epitaxial Pd-AlxGa1−xAs phase is correlated with the onset of ohmic behavior and may result in a thin solid phase regrown interfacial AlxGa1−xAs layer. An undoped 20 nm GaAs cap layer reduces ρc by about one order of magnitude. Ge/Pd contacts display greater dependence of ρc on x and much smoother surface morphology compared with those of standard Au-Ge-Ni contacts on AlxGa1−xAs (0≤x≤0.3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100872
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  • 5
    Electronic Resource
    Electronic Resource
    Optical detection of misfit dislocation-induced deep levels at InGaAs/GaAs heterojunctions (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 3572-3574 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using variable-depth luminescence excitation probes, we have observed discrete emission at characteristic energies from deep electronic states associated with misfit dislocations at InGaAs/GaAs interfaces. These states are localized near the buried heterointerface within the InGaAs layer and exhibit only minor variations in energy with composition and strain. The dislocation-induced spectral features appear only in strain-relaxed InGaAs films and are uncorrelated with additional features due to native bulk defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111201
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  • 6
    Electronic Resource
    Electronic Resource
    Hot-electron attenuation lengths in ultrathin magnetic films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5164-5166 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ballistic electron emission microscopy (BEEM) is used to measure hot-electron transport across magnetic metal multilayers. Room temperature measurements in air have been carried out on Au/M/Si(100), Au/M/Au/Si(100), and Au/M/PtSi/Si diodes, that were sputter deposited at 175 or 300 K, where M is Co, Fe, Ni, Cu, or Ni81Fe19. Plots of log BEEM current versus M thickness are linear giving hot-electron (1.5 eV) attenuation lengths (ALs), for Au/M/Si diodes (M=Co, Fe, Ni81Fe19, and Ni) of 0.3, 0.5, 0.8, and 1.3 nm, respectively (with typical standard uncertainties of ±10%). Magnetic metal sandwich diodes, (Au/M/Au/Si) show larger ALs, 0.8 and 2.1 nm, for M=Co and Ni81Fe19, respectively. PtSi interlayers improve the surface roughness but have little effect on the AL while low temperature depositions increase the AL. We presume that the increases in the AL are due to better microstructure, less silicide reaction, or to changes in elastic scattering at interfaces. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373417
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  • 7
    Electronic Resource
    Electronic Resource
    Generation of misfit dislocations in semiconductors (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4413-4420 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The acting slip mechanism for the generation of misfit dislocations in diamond-type–semiconductor heterostructures is investigated with transmission electron microscopy. It is shown that dissociation of the 60°-mixed dislocations can lead to a difference in strain accommodation for tensile and compressive strain. A strain/thickness relation is obtained from the energy expression for nucleation of half-loops. This relation is compared with other theoretical relations and with experimental strain data for Si/GaP(001) and In0.07Ga0.93As/GaAs(001) , measured with transmission electron microscopy and ion blocking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339078
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  • 8
    Electronic Resource
    Electronic Resource
    Lattice-strained heterojunction InGaAs/GaAs bipolar structures: Recombination properties and device performance (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1234-1236 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Double-heterojunction NpN GaAs/InxGa1−xAs/GaAs bipolar transistor layers have been grown by molecular-beam epitaxy, and large-area devices have been processed and characterized. The indium mole fraction in the strained base layer, and thus the band offsets, has been varied with significant differences in current gains. From the gain versus indium-composition relation a valence-band offset of ΔEv =9.7 meV/% In is derived. We found that the highest base-In content yields the highest-gain devices despite the presence of interface misfit dislocations and dark-line defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338179
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  • 9
    Electronic Resource
    Electronic Resource
    Nonalloyed ohmic contacts to n-GaAs by solid-phase epitaxy of Ge (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 942-947 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A low resistance nonalloyed ohmic contact to n-GaAs is formed which utilizes the solid-phase epitaxy of Ge through PdGe. Discussion focuses on the conditions necessary to attain low specific contact resistivity (∼10−6 Ω cm2 on 1018 cm−3 n-GaAs) and on the interfacial morphology between the contact metallization and the GaAs substrate. MeV Rutherford backscattering spectrometry and channeling show the predominant reaction to be that of Pd with amorphous Ge to form PdGe followed by the solid-phase transport and epitaxial growth of Ge on 〈100〉 GaAs. Cross-sectional transmission electron microscopy and lattice imaging show a very limited initial Pd-GaAs reaction and a final interface which is planar and structurally abrupt to within atomic dimensions. The presence of excess Ge over that necessary for PdGe formation and the placement of Pd initially in contact with GaAs are required to result in the lowest contact resistivity. The experimental data suggest a replacement mechanism in which an n+-GaAs surface region is formed when Ge occupies excess Ga vacancies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339705
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  • 10
    Electronic Resource
    Electronic Resource
    Anisotropic resistivity correlated with atomic ordering in p-type GaAsSb (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2384-2386 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have detected three- and six-fold lateral ordering in undoped and carbon-doped GaAs1−xSbx films (0.4〈x〈0.6), using plan-view and cross-sectional transmission electron microscopy. The samples were grown by organometallic vapor phase epitaxy onto oriented InP (001) substrates, at temperatures ranging from 500 to 600 °C. Spontaneous lateral superlattices with modulation parallel to the [110] in-plane direction occur with two periodicities, 6 or 3 times the random alloy 〈110〉 lattice parameter. The degree of ordering or domain size increases with growth temperature, as seen by increasing definition of the superlattice fringes in the images, and by a change from streaks to superlattice spots in the selected area diffraction patterns. While the formation mechanism is likely a surface mediated process, no differences were detected for samples in compression or tension, or between those undoped or carbon doped. The ordering correlates with large anisotropies of up to 150% in [110]/[11(underbar)0] sheet resistance ratios. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1406982
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