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  • 1
    Digitale Medien
    Digitale Medien
    Microstructures of (In,Ga)P alloys grown on GaAs by metalorganic vapor-phase epitaxy (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3077-3087 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The microstructures of metalorganic vapor-phase epitaxy alloys of (In,Ga)P grown on GaAs substrates were examined using transmission electron microscopy. Alloys examined were grown at 600–775 °C on substrates at or near (001) or (113)A using growth rates of 0.69 and 0.17 nm/s. Two common semiconductor alloy phenomenon, ordering and phase separation, were studied over this range of growth conditions. The CuPt-type ordering reflections are sharpest for growth at 675 °C and more diffuse at 600 and 725 °C due to higher densities of antiphase boundaries. Order can be eliminated by growth at 750 °C or above to obtain the highest band gaps and optical emission energies. Detailed investigation of the microstructure for growth at 675 °C indicates that ordered domains are platelets consisting of thin (1–2 nm) lamella on (001) planes that alternate between the two {111}B ordering variants, in agreement with a model proposed by others. We have formed "unicompositional'' quantum wells with sharply defined ordered layers between disordered barrier layers by changing growth temperature, which demonstrates that ordering is determined to a great degree by the conditions during growth. Phase separation is seen for the entire range of growth parameters, independently of ordering; its contrast shows modulations with a variable spacing ranging from a few nanometers to ∼100 nm. Implications of the coexistence of phase separation and ordering for growth models describing these phenomena are discussed. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358659
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  • 2
    Digitale Medien
    Digitale Medien
    Temperature dependent photoluminescent properties of InAsxP1−x/InP strained-layer quantum wells (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3041-3045 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Thermal quenching of photoluminescence from InAsxP1−x/InP strained-layer quantum wells has been investigated over the temperature range of 20–295 K. Structures with compositions of x=0.67 and x=1.0 and quantum well thicknesses of 1–17 monolayers were evaluated using Fourier transform photoluminescence spectroscopy. For InAs/InP heterostructures, the activation energy for thermal quenching depended on well thickness. Luminescence quenching was attributed to thermalization of free excitons from the well, and subsequent nonradiative recombination. Addition of phosphorus to the wells alters the recombination process responsible for luminescence quenching.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.351514
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  • 3
    Digitale Medien
    Digitale Medien
    Photoluminescence linewidths in metalorganic vapor phase epitaxially grown ordered and disordered InAlGaP alloys (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5397-5400 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The dependence of the photoluminescent properties of In0.48(AlyGa1−y)0.52P alloys (0≤y≤0.5) on growth temperature and substrate misorientation off GaAs(100) has been studied. Samples were grown using low-pressure metalorganic vapor phase epitaxy. By studying the dependence of ordering behavior in InGaP as a function of substrate misorientation and growth temperature simultaneously, a very large range in low-temperature photoluminescence emission energy—135 meV—has been obtained. The photoluminescence linewidth exhibits a strong, continuous dependence on the extent of atomic ordering (the emission energy) in the alloys. The results indicate that inhomogeneity in the microstructure of the material (i.e., between "ordered'' domains and the "disordered'' matrix) is the dominant photoluminescence broadening mechanism. This investigation has allowed a significant optimization of the optical properties of these materials, including the narrowest low-temperature photoluminescent linewidths reported for all of the In(AlyGa1−y)P alloys exhibiting direct band gaps (4.2 meV for InGaP).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.352354
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  • 4
    Digitale Medien
    Digitale Medien
    Optical properties of InAs/InP strained single quantum wells grown by organometallic vapor-phase epitaxy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 405-408 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The optical emission characteristics of highly strained InAs/InP single quantum wells prepared using atmospheric-pressure organometallic vapor-phase epitaxy have been studied. For well thicknesses of one to three monolayers (ML), the photoluminescence (PL) spectra exhibited intense emission in the energy range 1.15–1.3 eV, with typical full width at half maximum of 8–14 meV. The dependence of PL emission energy on well thickness for 1–5-ML-thick wells was compared with the results of a finite-well calculation, taking into account the effects of strain on the band structure. Good agreement between experiment and theory was obtained for a valence-band offset of 270 meV, consistent with recent reports for the InAs/InP system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.350289
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  • 5
    Digitale Medien
    Digitale Medien
    Monolayer abruptness in highly strained InAsxP1−x/InP quantum well interfaces (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1142-1144 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: InAsxP1−x/InP strained quantum well structures have been prepared by atmospheric-pressure organometallic vapor phase epitaxy (OMVPE). Structures with compositions of x=0.40–0.67 and quantum well thicknesses of 0.8–16 nm were evaluated using photoluminescence spectroscopy. Strain in the pseudomorphic wells ranged from 1.3 to 2.1%. Doublets and multiplets are observed in the photoluminescence spectra and are attributed to luminescence from regions in the wells differing in thickness by a single monolayer, with atomically smooth interfaces over areas greater in lateral extent than the exciton diameter. Typical full widths at half maximum of the photoluminescence from the thinnest wells are 8–14 meV, comparable to the best reported values for thin lattice-matched quantum wells prepared from the InGaAs(P)/InP system using OMVPE.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.100742
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  • 6
    Digitale Medien
    Digitale Medien
    InAs/InP strained single quantum wells grown by atmospheric pressure organometallic vapor phase epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1998-2000 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Strained InAs/InP single quantum wells of nominal thickness 1–11 monolayers have been prepared using organometallic vapor phase epitaxy in an atmospheric pressure reactor. For wells of thickness 1–3 ML grown using optimal flow modulation parameters, the surface morphology was specular and narrow single-line photoluminescent emission was observed. For thicker wells, the evolution of additional PL features and the appearance of island-like features on the sample surface was attributed to the onset of three-dimensional (island) growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.103989
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  • 7
    Digitale Medien
    Digitale Medien
    Transient photoinduced absorption in (AlxGa1−x)0.5In0.5P fractal quantum well heterostructures (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 966-968 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Picosecond photoinduced absorption measurements have been performed on four different (AlxGa1−x)0.5In0.5P fractal quantum well heterostructures. The results of these measurements reveal that, at early times following pulsed excitation, the carriers remain near the surface layer in which they were photogenerated, and populate the higher lying branches of the V-shaped fractal structure. With increasing time, the carrier population relaxes toward the lowest energy, central wall. The rate at which the relaxation occurs is governed by the characteristic layer of widths of the fractal structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.117097
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  • 8
    Digitale Medien
    Digitale Medien
    Microstructure of laterally oxidized AlxGa1−xAs layers in vertical-cavity lasers (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 19-21 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have studied the lateral oxidation of AlxGa1−xAs (x=0.98 and 0.92) layers contained in vertical-cavity lasers using cross-sectional transmission electron microscopy. We find a fine-grained (∼4 nm) cubic spinel phase of Al2O3 in both the 2% Ga- and 8% Ga-oxidized layers. The 8% Ga-oxidized layers contract vertically by 6.7% and not the expected 20% for a fully dense Al2O3 layer, with the 2% Ga-oxidized layers showing a similar contraction. We observe a ∼17-nm-thick amorphous interface between the oxidized and unoxidized AlxGa1−xAs layers, which may account for the excellent electrical properties of these devices. We also observe metastable amorphous cavities associated with the moving reaction front. We infer the reaction proceeds from an initial amorphous phase that then transforms to a porous γ-Al 2O3 layer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.118103
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  • 9
    Digitale Medien
    Digitale Medien
    Threshold investigation of oxide-confined vertical-cavity laser diodes (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3689-3691 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report an experimental and theoretical analysis of the threshold properties of infrared oxide-confined vertical-cavity surface emitting lasers. We find good agreement between experiment and theory on the wavelength dependencies of the threshold current density and intrinsic voltage. The threshold voltage is shown to equal the sum of the calculated quasi-Fermi energy separation and the ohmic drop arising from a record low 17 to 30 Ω series resistance in these vertical-cavity lasers. Our analysis provides two independent means for determining the material threshold gain. A threshold gain of 500 cm−1 is found for these oxide-confined lasers, which is half that estimated for ion-implanted lasers with inferior electrical and optical confinement. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.115744
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  • 10
    Digitale Medien
    Digitale Medien
    Improved AlGaInP-based red (670–690 nm) surface-emitting lasers with novel C-doped short-cavity epitaxial design (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 329-331 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A modified epitaxial design leads to straightforward implementation of short (1λ) optical cavities and the use of C as the sole p-type dopant in AlGaInP/AlGaAs red vertical-cavity surface-emitting lasers (VCSELs). Red VCSELs fabricated into simple etched air posts operate continuous wave at room temperature at wavelengths between 670 and 690 nm, with a peak output power as high as 2.4 mW at 690 nm, threshold voltage of 2.2 V, and peak wallplug efficiency of 9%. These values are all significant improvements over previous results achieved in the same geometry with an extended optical cavity epitaxial design. The improved performance is due primarily to reduced optical losses and improved current constriction and dopant stability. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.115434
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