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  • 1
    Electronic Resource
    Electronic Resource
    Determination of Landau level lifetimes in AlGaAs/GaAs heterostructures with a ps free electron laser (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1110-1112 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Previous determinations of Landau level lifetimes in GaAs/AlGaAs heterostructures from saturation cyclotron resonance measurements have been confused by heating effects. We have utilized a ps free electron laser to show that for samples with sheet concentration less than 3×1011 cm−2, true saturation of cyclotron resonance is observable at high magnetic fields, in the presence of polaron nonparabolicity. However, at higher concentrations, the polaron is screened and saturation is no longer possible. At low magnetic fields (i.e., long wavelengths) where the polaron nonparabolicity is negligible, saturation is not possible for any sheet density. It is confirmed that the lifetime of the first excited Landau level has an inverse dependence on carrier density. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114977
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  • 2
    Electronic Resource
    Electronic Resource
    Reverse biased photoconductive detectors and switches with separate absorption and detection area (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1367-1369 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on reverse biased photoconductive detectors with novel design and improved high-frequency performance. Taking advantage of the "giant ambipolar diffusion constant'' which has been observed previously in n-i-p-i doping superlattices very fast carrier transfer from the inner absorption area to the outer detection area is achieved. The combination of narrow contact spacings and small RC and diffusion time constants results in very high gain-bandwidth products ((approximately-greater-than)20 GHz) with adjustable 3 dB frequencies. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113203
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  • 3
    Electronic Resource
    Electronic Resource
    Fabrication of lateral npn-phototransistors with high gain and sub-μm spatial resolution (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 751-753 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel kind of phototransistor with high gain and sub-μm spatial resolution is fabricated by focused laser beam-induced Zn doping of an n-modulation doped GaAs/Al0.4Ga0.6As quantum well structure. To produce this lateral npn-structure, p-doped lines are directly written over a mesa without degrading the quality of the sample. The local Zn doping causes an effective potential barrier for electrons. Photogenerated holes reduce this barrier and amplify the thermionic electron current. Spatially resolved photocurrent measurements show typical responsivities above 103 A/W and linewidths as small as 605 nm. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114082
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  • 4
    Electronic Resource
    Electronic Resource
    Electric-field-induced exciton transport in coupled quantum well structures (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 232-234 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a conceptionally new approach to achieve electrostatically induced transport and confinement for spatially indirect excitons. Experimentally, exciton transport is demonstrated in an electric-field-tunable GaAs/AlAs coupled quantum well structure, which is configured as a three-terminal device. In spatially resolved photoluminescence experiments, it is shown that indirect excitons experience a drift field, which is given by an electrostatically induced band-gap gradient in the plane of the coupled quantum well structure. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114677
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  • 5
    Electronic Resource
    Electronic Resource
    Low temperature current imaging tunneling spectroscopy on wet chemically etched quantum wires (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 52-54 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, low temperature current imaging tunneling spectroscopy studies on wet chemically etched quantum wires are reported. On the wires, symmetric current voltage curves are observed. Between the wires, however, significant current is only observed for negative sample bias. Through this behavior, topographic and current imaging profiles of quantum wires are obtained. In liquid helium, the current profiles of the wires are clearly smaller than the topographic profiles, which is used to determined the edge depletion width directly. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118116
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of optical interference on quantum well infrared photodetectors in a 45° waveguide geometry (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 16-18 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Standing light waves caused by the interference of incident and reflected beams lead to a spatial modulation of the electromagnetic field within the active region of a quantum well infrared photodetector (QWIP). The optical excitation—determined by the electric field component perpendicular to the quantum well plane—is thus inhomogeneous, influencing the QWIP responsivity and its voltage dependence. The inhomogeneity can be suppressed by using mesa photodetectors where only half of the top contact is covered with metal. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123119
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  • 7
    Electronic Resource
    Electronic Resource
    Carrier cooling and recombination heating in intermixed GaAs/AlGaAs quantum wires and dots (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1333-1337 
    Details
    ISSN: 0392-6737
    Keywords: Time resolved optical spectroscopies and other ultrafast optical measurements in condensed matter ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The cooling of photoexcited hot carriers in 2D, 1D and 0D systems is studied experimentally. In comparison with a theoretical carrier relaxation model which holds for 2D and 1D systems, it is found that preferably recombination and a weaker electron-LO-phonon interaction dominates the carrier dynamics with decreasing dimensionality. Consequently, we conclude a less dominant role of hotphonon effects in 0D and 1D systems compared to 2D systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457205
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  • 8
    Electronic Resource
    Electronic Resource
    A laser dry etch process for smooth continuous relief structures in InP (1996)
    Springer
    Applied physics 63 (1996), S. 415-419 
    Details
    ISSN: 1432-0630
    Keywords: 81.40 Z ; 81.60 Z ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A laser induced etch process is described which uses a pulsed 248 nm KrF excimer laser and Cl2 atmosphere for the fabrication of monolithic continuously curved reliefs in InP substrate. In a bakeable processing chamber with low base pressure a wide range of laser fluences is available for damage-free etching. Especially, by photothermal heating far above the melting point, mirrorlike smooth surfaces are obtained. The etch rate characteristics are correlated to the maximum surface temperature reached during the laser pulse. The etch rate is independent of pressure and gas flux in the ranges 0.1–10 mbar and 20–300 sccm, respectively. It increases, however, with the background substrate temperature. Etch rates of up to 3.6 nm/pulse or 4.3 lm/min are possible at 20 Hz pulse repetition rate without visible surface damage. The process exhibits a smooth increase of the etch rate from 1 to 3 nm/pulse between 200 and 300 mJ/cm2, which could be used for making curved reliefs by optical transmission variations on the projection mask.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01571666
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  • 9
    Electronic Resource
    Electronic Resource
    Laser-induced dry etching of integrated InP microlenses (1997)
    Springer
    Applied physics 65 (1997), S. 349-353 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 81.40 Z; 81.60 Z; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050590
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  • 10
    Electronic Resource
    Electronic Resource
    A laser dry etch process for smooth continuous relief structures in InP (1996)
    Springer
    Applied physics 63 (1996), S. 415-419 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 81.40 Z; 81.60 Z; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  A laser induced etch process is described which uses a pulsed 248 nm KrF excimer laser and Cl2 atmosphere for the fabrication of monolithic continuously curved reliefs in InP substrate. In a bakeable processing chamber with low base pressure a wide range of laser fluences is available for damage-free etching. Especially, by photothermal heating far above the melting point, mirrorlike smooth surfaces are obtained. The etch rate characteristics are correlated to the maximum surface temperature reached during the laser pulse. The etch rate is independent of pressure and gas flux in the ranges 0.1–10 mbar and 20–300 sccm, respectively. It increases, however, with the background substrate temperature. Etch rates of up to 3.6 nm/pulse or 4.3 μm/min are possible at 20 Hz pulse repetition rate without visible surface damage. The process exhibits a smooth increase of the etch rate from 1 to 3 nm/pulse between 200 and 300 mJ/cm2, which could be used for making curved reliefs by optical transmission variations on the projection mask.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01571666
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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