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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3821-3828 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the results of a systematic investigation of radiative recombination processes of the free-carrier plasma confined in Ga0.47In0.53As/Al0.48In0.52As multiple-quantum-well structures on InP substrate, either undoped or modulation doped. Photoluminescence under low- and high-excitation intensity, luminescence excitation, and optical gain measurements have been used to study the electronic transitions and the optical amplification in the temperature range 10–300 K. Space-resolved luminescence has also been adopted to distinguish between the spontaneous and the stimulated spectral contributions to the observed luminescence collected along different directions with respect to the [001] growth axis of the heterostructures. Optical gain up to 300 K has been observed in the undoped samples under photoexcitation quasiresonant with the confined states in the quantum wells. The theoretical analysis of the optical gain spectra furnishes quantitative data on the electron-hole plasma ground level. In the n-type modulation-doped samples the application of intense optical pumping allows us to observe the transition from the one-component electron plasma to a two-component electron-hole plasma through the rising of a sharp stimulated emission in the optical spectra. Also in this case we observe optical gain up to room temperature.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1182-1188 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The generation rates and annealing behavior of the irradiation defects in n- and p-type hydrogen-grown float-zoned silicon (irradiated with γ rays from 60Co) have been studied by the deep-level transient spectroscopy technique and compared with those of irradiated argon-grown float-zoned silicon. Assuming the generation rate of the irradiation defects created by γ rays in argon-grown float-zoned silicon is 1, then the generation rates of the A center, divacancy, and phosphorus vacancy in n-type hydrogen-grown float-zoned silicon are 0.23, 0.78, and 0.19, respectively, while the generation rates of the divacancy and H(0.37 eV) in p-type hydrogen-grown silicon are 0.79 and 0.10, respectively. Due to the existence of hydrogen, the generation rate reduction of the major irradiation defects in γ-ray irradiated silicon is more pronounced than that in 1-MeV electron irradiated silicon. Three hydrogen-related defects, H(0.10 eV), H(0.29 eV), and H(0.56 eV), were seen in γ-ray irradiated hydrogen-grown float-zoned silicon, among which H(0.10 eV) and H(0.56 eV) were reported by us to exist in electron irradiated hydrogen-grown float-zoned silicon, while H(0.29 eV) is reported for the first time. The convergence effect of annealing temperatures for the irradiation defects was observed. That is, the annealing temperatures at which the irradiation defects diminish are almost the same for most irradiation defects, similar to that in the case of electron irradiation, was observed, showing that this effect is characteristic of the hydrogen behavior in silicon, and irrelevent to the type of irradiation.
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the crystalline and optical properties of AlyIn1−yAs ternary alloys grown by molecular beam epitaxy on InP substrates. We obtain Al0.48In0.52As layers with both high structural quality and excellent optical performance by growing (i) at high substrate temperature (600 °C), (ii) on a high-quality GaxIn1−xAs/AlyIn1−yAs short-period superlattice buffer, (iii) or on a high-quality GaxIn1−xAs buffer layer, as attested by double-crystal x-ray diffraction and photoluminescence measurements. In addition the experimental results indicate a significant reduction of the clustering level in these samples which is interpreted in terms of a smoothing of the growth front, a thermodynamically controlled growth mode, and the interplay between In segregation and In desorption. Our investigations further show that the improvement of the structural quality and of the optical performance are strongly correlated. Finally, we report the first evidence of excitonic features in photoluminescence excitation spectra of the AlyIn1−yAs ternary alloy.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 1968-1970 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep levels in semi-insulating (SI) InP obtained by annealing in iron phosphide (IP) ambiance have been characterized by optical transient current spectroscopy (OTCS). Compared with the OTCS result of the SI InP prepared by annealing in pure phosphorus (PP) ambiance, the IP SI InP presents only two traps with activation energies of 0.20 and 0.63 eV, respectively. The results suggest that the diffusion of Fe-atoms suppresses the formation of a few defects in the IP SI InP. The nature of deep levels in the IP and PP SI InP has been discussed on the basis of these results. The relation between material property and defects in those SI InP has also been revealed. © 2002 American Institute of Physics.
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a novel semiconductor quantum well (QW) structure consisting of alternating (In,Ga)As and Ga(P,As,Sb) layers grown pseudomorphically on a GaAs substrate by all-solid-source molecular beam epitaxy. The band gap of the QW is determined by the thickness and composition of both types of layers and can be varied from 1.1 to 1.55 μm. Calculations show that the observed strong room-temperature photoluminescence in this wavelength range can be explained by a type-II transition in the QW. Structural investigations by reflection high-energy electron diffraction, transmission electron microscopy, and secondary ion mass spectroscopy confirm a triple layer structure with laterally modulated composition. Photoluminescence measurements reveal a linewidth of 50 meV at 1.3 μm and a luminescence decay time of 240 ps. Our investigations demonstrate the feasibility of this materials system for vertical cavity surface-emitting lasers and other optoelectronic devices on GaAs. © 2000 American Institute of Physics.
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work we report on transmission electron microscopy and high-resolution x-ray diffractometry studies of lattice matched AlxIn1−xAs/InP and GayIn1−yAs/InP epilayers grown by molecular beam epitaxy on InP(100) substrates. High-resolution and diffraction contrast electron microscopy measurements show the presence of different contrast zones in the epilayers. The analysis of high-resolution x-ray diffraction measurements and computer simulations ascribe these zones to the presence of a compositional gradient in the epilayers. A comparison among investigated samples grown under slightly different growth conditions combined with an analysis of the crystal defects is presented. Growth-induced small variations in the chemical composition of the epilayer can produce differences in the structural quality of the epitaxial layer. Finally, a few monolayers thick and highly strained film of InAsP, is observed in all investigated samples at the substrate/epilayer interface. The formation of this interface layer is explained by the exchange of As and P during exposure of the InP surface to As4 before the growth. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1921-1923 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Use of a cracked Sb source and a postgrowth anneal procedure has been found to yield significant improvements in optical efficiencies of GaInSb/InAs superlattices grown by molecular beam epitaxy. Appreciable 5 μm band-to-band luminescence has been observed at room temperature, and stimulated emission at 3.2 μm has been demonstrated in an optically pumped structure. Intrinsic properties of this class of superlattices favor them for application as efficient infrared lasers operating at comparatively high temperatures. © 1995 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 149-151 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed strain analysis of high resolution x-ray diffraction patterns taken from GaxIn1−xAs and AlyIn1−yAs layers grown lattice matched on (001) InP substrates shows the existence of distinct interface regions. Our dynamical diffraction model allows us to detect buried interface layers with submonolayer resolution and differences in composition of less than 1% from the rest of the epilayer. Comparison between experimental and theoretical rocking curves reveals that the interface region between epilayer and substrate comprises 2 monolayers InAs plus GaxIn1−xAs (or AlyIn1−yAs) interlayer with different group III element ratios.
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1830-1832 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a study on gamma irradiated porous Si. The electron paramagnetic resonance study on porous Si irradiated by gamma rays shows that the observed signals come from an intrinsic defect, a Si dangling bond, at the interface of Si/SiOx in porous Si. The photoluminescence measurements show that the gamma irradiation not only increases the intensity of the photoluminescence but also greatly improves its stability. The spectra of the Fourier transform infrared absorption show that the gamma irradiation is an effective method for accelerating oxidation of porous Si. All experimental results can be explained by the increase of the oxidation layer thickness which decreases the nonradiative recombination probability of electron-hole pairs.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3700-3702 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the characterization of a set of broad-area semiconductor diode lasers with mid-wave infrared (3–5 μm) emission wavelengths. The active region of each laser structure is a 5- or 6-period multiple quantum well (MQW) with Ga0.75In0.25As0.22Sb0.78 barriers and type-II (broken-gap) Ga0.75In0.25Sb/InAs superlattice wells. The cladding layers of each laser structure are n- and p-type InAs/AlSb (24 A(ring) /24 A(ring)) superlattices grown lattice-matched to a GaSb substrate. By tailoring constituent layer thicknesses in the Ga0.75In0.25Sb/InAs superlattice wells, laser emission wavelengths ranging from 3.28 μm (maximum operating temperature=170 K) to 3.90 μm (maximum operating temperature=84 K) are obtained. © 1995 American Institute of Physics.
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