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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 2447-2456 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Ruff–MKW boiling point method is used to determine equilibrium vapor pressures greater than 660 Pa (5 Torr). Samples are vaporized from a Ruff cell, which has a capillary exit, in the presence of an inert gas. Viscosity coefficients and gaseous interdiffusion coefficients may be determined also. This is a second study of the method using Cd(l) and Zn(l) as samples. For the first study with CsCl(l), see J. Chem. Phys. 81, 915 (1984). Vapor pressure data are in good agreement with previous data and gave a third-law ΔsubH0(298) for Cd(s) of 111.95±0.42 kJ/mol and for Zn(s) of 130.65±0.48 kJ/mol. Analyses of the diffusion coefficients gave atomic diameters of 4.06×10−10 m for Cd and 3.46×10−10 m for Zn; these values are somewhat larger than previously measured values. In these experiments when the equilibrium vapor pressures were greater than 13 000 Pa (100 Torr), the need to consider heat transfer from the furnace to the vaporizing sample was noted, i.e., sample cooling occured due to rapid vaporization. Validity of the MKW analysis was found.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 23 (1987), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The well field serving the Lyons Ferry Fish Hatchery has experienced reduced water temperatures following continued, periodic withdrawal of large volumes of water. In January 1985, the well field temperature was 49°F, which is less than the optimal 52°F for raising salmon and steelhead trout. The aquifer supplying the hatchery is in hydraulic and thermal connection with the Snake River and a flooded embayment of the Palouse River. Ground-water temperatures in the well field cycle on an annual basis in response to changes in surface water temperature and pumping rate. Numerical simulation of the well field, using a simplified mixing cell model, demonstrates the coupling of well field hydraulics and aquifer thermal response. Alternative pumping schedules indicate that it is feasible to adjust ground-water pumping to effectively store heat in the aquifer during the summer months when surface water temperatures are elevated. Sensitivity analysis of this model indicated that the primary controls of the system's thermal response are the volume of the aquifer assumed to contribute to the well field and temperature of the overlying surface water body.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 531-533 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first integrated injection-locked high-power continuous-wave diode laser array with an on-chip independently controlled master laser. This device emits a near-diffraction-limited (0.5° full width at half maximum) single-lobed far-field emission beam at single-facet powers up to 125 mW. Also, by current tuning the emission wavelength of the master laser, we observe steering of the single-lobed emission over an angular range of 0.50° at a rate of −1.2×10−2 deg/mA. Our work demonstrates the feasibility of incorporating active optical injection and control in the structure of high-power diode laser devices.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1127-1128 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Virtually total suppression of carrier-driven photochemical etching of semi-insulating GaAs, n-GaAs, and n+-GaAs has been achieved by indiffusion of Zn to a surface carrier concentration greater than 1020/cm3. This technique for photochemical reaction suppression can be used as a self-aligned etching technology for semiconductor device fabrication.
    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 66 (1989), S. 459-462 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained GaAs/InGaAs/AlGaAs quantum-well structures grown on GaAs have been removed from their original substrates by a lift-off process and bonded directly to glass or SiO2-coated Si substrates. Both undoped and modulation-doped structures have been characterized before and after transfer by Hall measurements, variable temperature x-ray diffraction, and photoluminescence. The bonded structures retain the high quality of the as-grown layers.
    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 62 (1987), S. 4182-4186 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a systematic microstructural study of enhanced lateral porous silicon formation in the buried p+ layers of n/p+/p− and p−/p+/p− structures. We find, surprisingly, extremely selective porous silicon formation due to the thin p+ layer in both structures, despite the absence of a p-n junction in the p−/p+/p− structure. The interface between the isolated island and the buried porous silicon layer was always located at the depth where the net p-type dopant concentration was 1–8×1015/cm3. The observed microstructure can largely be understood in terms of a recent model for porous Si formation in uniformly doped Si, proposed by Beale et al. [J. Cryst. Growth 73, 622 (1985)]. However, we also observe, for the first time, important effects unique to a nonuniform dopant concentration.
    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 60 (1986), S. 1131-1134 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have examined the properties of (InGa)As/GaAs strained-layer superlattices (SLSs) that have been disordered by implantation of 5×1015/cm2, 250 keV 64Zn+ followed by controlled atmosphere annealing at 680 °C for 30 min. Ion channeling techniques indicate that the Zn-disordered regions of the SLS contain extensive crystalline damage after annealing. Simulations of the disordering process using an analytic ion range code predict that the electrical junction resulting from the implantation process is located outside the disordered region of the SLS in both the vertical and the lateral directions. Junction electroluminescence intensity for given drive current densities from the Zn-disordered SLS devices is comparable to that from reference Be-implantation-doped (SLS retained) devices and greatly exceeds that from heavily dislocated grown-junction mesa diodes in the homogeneous alloy of the average SLS composition; this result is consistent with the results of the simulations. This study demonstrates that implantation disordering can be as useful for strained-layer systems as for less severely mismatched heterojunction systems.
    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 60 (1986), S. 3631-3640 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have characterized the effects of Be+ implantation and controlled-atmosphere annealing on the structure of Ga(AsP)/GaP strained-layer superlattices (SLSs). Damage and strain distributions within the implanted layers were examined by cantilever-beam bending measurements, double-crystal x-ray rocking curves, and a variety of ion-channeling techniques. Implantation-induced displacement damage produces additional stress in the SLS, in this case reaching 4.5×109 dyn/cm2, a value comparable to that of the built-in stresses in these SLSs. The depth distribution of ion damage as measured by ion channeling agrees well with the predictions of the trim code, although substantial recovery occurs during the room-temperature implant. Rocking curve analysis indicates that the interlayer strain in the SLS is retained despite the ion damage, and that the ion damage can be modelled as an independent additional source of strain in the as-implanted structure. The linear expansion of the layers due to point defect generation for the 1×1015 Be/cm2 implant is determined to be approximately 0.3% by all three techniques. After controlled-atmosphere annealing at the nominal SLS growth temperature, both the x-ray and ion-channeling measurements indicate removal of the implant damage with the as-grown strain retained and no resolvable intermixing of the layers in the SLS. These results demonstrate that ion-implantation technologies developed for bulk semiconductors can successfully be applied to strained-layer superlattice systems.
    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 65 (1989), S. 4769-4773 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent studies have provided sufficient knowledge about the dominant failure mechanisms for lattice-mismatched strained-layer heterostuctures to permit the design of thermodynamically stable strained-layer systems for device applications. We have developed procedures that summarize this knowledge for the working device designer, and apply these relationships to the design of ion-implanted, strained-layer, quantum-well lasers.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the properties of Ga(AsP)/GaP strained-layer superlattices (SLSs) that have been doped by implantation of 1×1015/cm2, 75 keV Be+ followed by controlled-atmosphere annealing at 825 °C for 10 min. Our results indicate that doping of these strained-layer superlattices without disordering is a viable process. Liquid-helium temperature photoluminescence suggests a binding energy for the implanted acceptors of 50 meV, consistent with that of beryllium in GaP-based alloys. The implantation-doped regions exhibit room-temperature electrical activation of 15% and hole mobilities of 20 cm2/V s, consistent with the values expected for type-converted GaP-based alloys. SLS diodes fabricated by this process exhibit excellent rectification properties, with a forward turn-on voltage of approximately 1.8 V and low values of room-temperature reverse leakage current densities. Diodes formed from SLSs with original n-type doping of 1×1017/cm3 have typical reverse leakage current densities of 1×10−7 A/cm2 at −10 V, despite the depletion region penetrating approximately ten interfaces of the SLS at this bias. Deep-level transient spectroscopy demonstrates the existence of defect centers, whose densities and signatures are similar to those found in ion-implanted GaP. The implanted photodiodes exhibit a wavelength-dependent photoresponse characteristic of grown-junction SLS photodetectors in the same chemical system. Examination of the spatial response of the photodiodes to a tightly focussed (FWHM=2.45 μm) laser beam at a wavelength of 488 nm indicates that the photoresponse from the device is uniform to within 10% for regions away from the edges of the implanted regions. Modelling of the wavelength-dependent and the spatially dependent photoresponse allows an estimate of minority-carrier diffusion lengths for electrons and holes of 1.0 μm parallel to the SLS layers and 0.1 μm perpendicular to the SLS layers. The excellent electrical and optical properties of the implanted and annealed SLS materials implies additional device applications for these novel materials.
    Type of Medium: Electronic Resource
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