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  • 1
    Electronic Resource
    Electronic Resource
    Origin of the bimodal distribution of low-pressure metal-organic-vapor-phase-epitaxy grown InGaAs/GaAs quantum dots (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3859-3863 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation process of a bimodal distribution of low-pressure metal-organic-vapor-phase-epitaxy (LP–MOVPE) grown InGaAs/GaAs quantum dots (QDs) is studied by transmission electronic microscopy. We demonstrate that in our growth conditions, the deposition of an InGaAs layer on an already existing array of InAs formed QDs leads to the nucleation of a second dots population. The InAs QDs nucleation is diffusion limited, inducing a low dots density due to the high In-atoms diffusion length typical of the MOVPE. On the contrary, the InGaAs QDs nucleation is enhanced by the roughness of the highly strained wetting layer of the InAs QDs, leading to higher density. The study of the photoluminescence spectra shows that the nucleation of InGaAs only occurs when the deposited InAs thickness exceeds about 1.4 monolayers, i.e., after the formation of the InAs QDs. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448887
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  • 2
    Electronic Resource
    Electronic Resource
    Kinematic versus dynamic approaches of x-ray diffraction simulation. Application to the characterization of InGaAs/InGaAlAs multiple quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2332-2336 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comparison of kinematic and dynamic approaches of x-ray diffraction is made for multiple InGaAs/InGaAlAs quantum wells (MQW), around 002 and 004 reflections, as a function of strain and thickness. A domain of validity of the kinematic approximation is then defined. It turns out that the kinematic approximation is sufficient in the case of typical structures for MQW lasers or modulators. An automatic procedure including kinematic treatment of double-diffraction X and photoluminescence data is proposed, which allows us to determine precisely the compositions, thicknesses, and even the band offsets of MQW structures. This procedure is applied to a 20 period sample. The results are confirmed by transmission electron microscopy measurement. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361159
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  • 3
    Electronic Resource
    Electronic Resource
    Electrochemical study of the degradation of vitamin K3 and vitamin K3 bisulfite (1979)
    s.l. : American Chemical Society
    Analytical chemistry 51 (1979), S. 752-757 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50042a040
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  • 4
    Electronic Resource
    Electronic Resource
    Metal organic vapor phase epitaxy growth of GaAsN on GaAs using dimethylhydrazine and tertiarybutylarsine (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2861-2863 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAsN layers with good structural quality and surface morphology have been successfully grown on a GaAs substrate using atmospheric pressure metal organic vapor phase epitaxy. A new combination of precursors namely, dimethylhydrazine for nitrogen and tertiarybutylarsine instead of conventional arsine for arsenic, greatly facilitated growths at temperatures as low as 500 °C. Layers with N content as high as 3% and corresponding to room temperature photoluminescence (PL) peak wavelength of 1.17 μm (1.064 eV) have been obtained. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119025
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  • 5
    Electronic Resource
    Electronic Resource
    1.3 μm strain-compensated InAsP/InGaP electroabsorption modulator structure grown by atmospheric pressure metal–organic vapor epitaxy (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 96-98 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality 15-period strain-compensated InAsP/InGaP electroabsorption (EA) modulator structures have been grown by atmospheric pressure metal–organic vapor epitaxy. The incorporation of large compressive strain (∼1.7%) in the InAsP wells and tensile strain (∼−1.8%) in the InGaP barriers necessitated the growth of a few InP monolayers between the wells and barriers. The high structural quality of such samples has been demonstrated by (cross-sectional transmission electron microscopy analysis to be free of misfit dislocations and thickness undulations. The detection of a sharp and abrupt room-temperature exciton peak both in the photoconductivity and photoluminescence measurements further confirmed their excellent optical quality. 100 μm cavity length EA modulators fabricated in these structures exhibited excellent performances namely, an extinction ratio higher than 20 dB for 2.5 V drive voltage, a 3 dB bandwidth over 20 GHz, and low coupling losses to fiber (less than 2.5 dB per facet). © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119319
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  • 6
    Electronic Resource
    Electronic Resource
    Structure of the GaAs/InP interface obtained by direct wafer bonding optimised for surface emitting optical devices (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 4892-4903 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Wafer bonding is increasingly used to fabricate heterostructures which cannot be obtained by conventional epitaxial growth because they involve highly mismatched materials. We have optimised the GaAs/InP bonding process in order to realise long wavelength microcavity devices combining advantageously high reflectivity AlGaAs Bragg reflectors with an InP-based active material. The bonded interface has been studied by transmission electron microscopy. Three dislocation networks are found at the interface. The first one accommodates both the lattice mismatch and the inevitable twist between the two crystals whereas the second one accommodates the tilt resulting from the slight vicinality of the initial surfaces. Our experiments strongly suggest that the third network forms upon cooling the structure. Between the dislocation lines, the crystal structure is perfectly reconstructed across the interface, with no amorphous materials present, except for cavities which occupy a few percent of the bonded area. The geometry and distribution of these cavities can be studied by imaging the first dislocation network. In light of these results, we discuss the mechanisms operating during the formation of the interface. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366353
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  • 7
    Electronic Resource
    Electronic Resource
    Inhibition of thickness variations during growth of InAsP/InGaP and InAsP/InGaAsP multiquantum wells with high compensated strains (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2279-2281 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate by using transmission electron microscopy that the insertion of small amounts of a well-chosen material lattice matched to the substrate at the interfaces between the highly strained layers of a strain-compensated multiquantum well (MQW) may prevent the catastrophic morphological degradation of the epitaxial structure as growth proceeds. For InAsP/InGaP and InAsP/InGaAsP MQWs grown on an InP substrate, we find that InP itself is an efficient interfacial material, whereas for the same InAsP/InGaAsP MQWs, an InGaAsP alloy is less effective. We show that the interfacial InP restores the planarity of the growth surface by filling the depressions of the underlying undulating strained layer. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117533
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of light- and heavy-ion-irradiated quantum-wells for use as ultrafast saturable absorbers (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2722-2724 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have compared light- and heavy-ion irradiation of InGaAs/InAlAs multiple-quantum wells for ultrafast saturable absorption applications. Under heavy-ion impacts, defect clusters were produced, as observed via transmission electronic microscopy. By contrast, in proton-irradiated samples, only point defects were formed. Nonlinear absorption measurements were performed with excitonic resonance pumping. The relaxation time of absorption saturation (minimum value 2 ps) did not depend on the irradiating ion, and was practically independent of the pulse repetition rate (up to 10 GHz) and optical excitation fluence (0.1 mJ/cm2). We conclude that irradiating multiple-quantum wells with light ions is as effective as using heavy ions, when fabricating ultrafast saturable absorber devices operating at high bit rate and near bandedge wavelength. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1408602
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrafast saturable absorption at 1.55 μm in heavy-ion-irradiated quantum-well vertical cavity (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1371-1373 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of absorption saturation in heavy-ion-irradiated InGaAs/InAlAs multiplequantum-well reflection-mode vertical-cavity devices have been performed with short pulses at 1.55 μm and repetition rates up to 10 GHz. The relaxation time was essentially independent of the pulse repetition rate and optical excitation fluence, with a lower value of 2.4 ps for an ion dose of 1012 cm−2. Efficient optical switching was obtained, with a saturation energy smaller than 12 pJ, a contrast ratio up to 3.5:1, and a switching amplitude up to 20% of the incident signal. A relaxation model accounting for capture and recombination on defect levels indicates an upper limit of 2 ps of the defect level recombination time. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126035
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  • 10
    Electronic Resource
    Electronic Resource
    Step-bunching instability in strained-layer superlattices grown on vicinal substrates (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 306-308 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial structures containing either compressive or tensile InGaAsP layers separated by InP layers were grown on variously misoriented vicinal (001) InP substrates and studied by transmission electron microscopy. Except for zero misorientation, the compressive layers develop long-wavelength asymmetrical lateral thickness modulations. We demonstrate that the associated surface undulation consists of periodic bunches involving only the initial substrate steps. With increasing misorientation, the wavelength of the modulation and its phase shift between successive layers decrease, whereas its amplitude increases. On the other hand, all tensile layers develop short-wavelength localized symmetrical thickness variations often involving facets. For intermediate misorientations, they also display undulations similar to those observed in compressive layers. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125728
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