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  • 1
    Electronic Resource
    Electronic Resource
    Stark ladders in piezoelectric superlattices (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1775-1779 
    Details
    ISSN: 0392-6737
    Keywords: Electron states in low-dimensional structures (including quantum wells, superlattices, layer structures, and intercalation compounds) ; Dielectric, piezoelectric, and ferroelectric materials ; Electrooptical effects ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary We describe an experimental and theoretical investigation of Wannier-Stark ladders in the optical spectra of (111)B InGaAs/GaAs piezoelectric superlattices. A unique feature of these structures is that an external electric field can be used to produce a flat superlattice—that is zero overall potential drop per period—in which there are large, opposing fields in the well and barrier. These fields cause a spatial separation of the electron and hole wave functions in the axial direction, leading to Stark ladderss which are intermediate between Type I (electrons and holes together) and Type II (electrons and holes separated by half a period) in character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457279
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  • 2
    Electronic Resource
    Electronic Resource
    Strained layer (111)B GaAs/InGaAs single quantum well lasers and the dependence of their characteristics upon indium composition (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4689-4696 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied a series of (111) oriented GaAs–InGaAs single quantum well, broad area lasers with active regions containing a range of indium concentrations, x, in order to understand the advantages and limitations of pseudomorphic strain. For x≤0.3, both an increased emission wavelength and reduced threshold current were observed with increasing x. The predominant cause of the wavelength increase is the reduction in bulk InGaAs band gap. The reduction in threshold current is attributed mainly to the reduced in-plane density of states caused by the strain induced lifting of the heavy and light hole degeneracy at the valence band edge. For x〉0.3, we see a marked deterioration in laser performance. However, we believe that this deterioration is not directly associated with strain relaxation at layer thicknesses beyond the critical value. Rather, imperfections in the AlGaAs cladding layers appear to seed the formation of dislocations within the strained regions. Within the limitation of strain relaxation, we observed monomode continuous wave emission at room temperature at wavelengths up to 1.072 μm and with threshold current densities as low as 74 A/cm2. The differential gain of 1.45×10−15 cm2 is around four times higher than measured on unstrained GaAs/AlGaAs single quantum well lasers. Like the reduction in threshold current density, this relatively high value is attributed to the strain induced reduction in the in-plane, heavy hole effective mass. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1359155
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  • 3
    Electronic Resource
    Electronic Resource
    Fokker–Planck model for nonlocal impact ionization in semiconductors (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1314-1317 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The probability distribution function (PDF) for impact ionization path length is a crucial quantity for understanding and modeling the low noise behavior of avalanche photodiodes with short multiplication regions. In such devices the ionization coefficient is no longer in equilibrium with the local electric field but depends on the carrier's history. The high electric fields needed to produce avalanche gain narrow the PDF, thereby reducing the randomness in ionization position and hence the noise in the multiplication. In this article we present a method for calculating PDFs using a Fokker–Planck model. The results are compared with those obtained from an equivalent Monte Carlo simulation employing a parabolic energy band, deformation potential optical phonon scattering, and a hard energy threshold for impact ionization. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1384854
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  • 4
    Electronic Resource
    Electronic Resource
    Wetting transition in squalane on a silanized diatomaceous gas chromatographic support (1985)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 89 (1985), S. 2571-2576 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100258a029
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  • 5
    Electronic Resource
    Electronic Resource
    Carrier screening effects in piezoelectric strained InGaAs/GaAs quantum wells grown on the [111]B axis (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5447-5452 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Excitation-power-dependent blue shifts in photoluminescence and electroluminescence are studied in piezoelectric strained layer multiple quantum wells (MQWs) incorporated in p-i-n diodes. By investigating MQWs with different geometric structures and controlling external bias it is demonstrated that, in contrast to previous studies, these blue shifts cannot always be attributed to long-range screening across a MQW and that screening must take place due to charge redistribution within individual wells. The results provide design rules to ensure this latter screening mechanism, which is subject to fast recovery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357202
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  • 6
    Electronic Resource
    Electronic Resource
    AN INVESTIGATION OF THE SYNERGISMS BETWEEN D-TUBOCURARINE CHLORIDE AND THIOPENTONE (1951)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 6 (1951), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1951.tb01369.x
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  • 7
    Electronic Resource
    Electronic Resource
    Impact ionization probabilities as functions of two-dimensional space and time (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2742-2751 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The impact ionization probability functions, P(x), are effectively histograms of the positions carriers ionize along the field direction, x, which determine the avalanche multiplication properties of a semiconductor device. In this work, we use a Monte Carlo model to investigate the form of these as multidimensional functions; in not just x, but also of the elapsed time, t, and the distance traveled perpendicular to the electric field direction, y. Despite most previous temporal calculations of the avalanche process assuming that all carriers travel at the drift velocity, vd, it is shown that electrons which ionize at the shortest distances travel several times faster than vd. There is also a significant spread in possible velocities with which ionizing carriers travel along the x direction due to diffusion. Diffusive spreading of the ionization probability in both x and y is also described. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1342190
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  • 8
    Electronic Resource
    Electronic Resource
    Impact ionization in AlxGa1−xAs/GaAs single heterostructures (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4363-4369 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Impact ionization involving transport across a single heterojunction has been studied by measuring the electron and hole initiated multiplication, Me and Mh, in a series of p+in+ AlxGa1−xAs(500 Å)/GaAs(500 Å) heterostructures with x ranging from 0.3 to 0.6. At low electric fields, because of dead space effects, Me and Mh in these devices are very different and are primarily determined by the ionization properties of the material in the latter half of the structure. As the electric field increases, feedback from the opposite carrier type causes Me and Mh to converge to the values measured in the equivalent alloy. The effects of the band-edge discontinuities at the heterojunction interface on Me and Mh in these heterostructures are compensated by the different energy-loss rates in AlxGa1−xAs and GaAs. A simple Monte Carlo model using effective conduction and valence bands is used to interpret the experimental results. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368656
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  • 9
    Electronic Resource
    Electronic Resource
    Treatment of soft threshold in impact ionization (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 2538-2543 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The avalanche multiplication and excess noise properties of a range of submicron Si diodes have been measured and analyzed using a model for impact ionization which includes the effect of dead space, modified to allow for a gradual onset of ionization, with realistic threshold energies. Good agreement is achieved between the predictions of this "soft dead space" model and measurements of multiplication and excess noise, both on a range of submicron diodes with uniform electric fields and also on a p+n diode with a highly nonuniform electric field. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1388865
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  • 10
    Electronic Resource
    Electronic Resource
    Simulated current response in avalanche photodiodes (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2107-2111 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The time dependent current response to an impulse of injected carriers is calculated for an avalanche photodiode using Monte Carlo simulation. For low electric fields and long avalanche regions the results agree with the conventional model, which assumes that carriers travel always with their saturated drift velocities. However, while diffusion remains unimportant, for high fields and short avalanche regions, the conventional model underestimates the device speed. Monte Carlo simulations show that the mean downstream average velocity of ionizing carriers is significantly enhanced at high electric fields and agreement is restored if we allow for this effect in the conventional model. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1432122
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