ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 797-799 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlxGa1−xAs–GaAs–InyGa1−yAs quantum well heterostructure lasers with thin sharply defined cavities that operate longitudinally or vertically are demonstrated. Longitudinally, the cavity is defined by cleaving (edge emission) while vertical definition is provided by a lower AlxOy/GaAs distributed Bragg reflector (DBR) and an upper SiO2/Si DBR that form a resonant structure. A reverse-biased tunnel contact junction provides lateral electron current to support hole injection through a native-oxide-defined aperture. This ultrathin cavity configuration produces low threshold high efficiency (η∼91%, L=140 μm) edge emission (longitudinal operation) in the case of long lasers (L(approximately-greater-than)90 μm), and vertical emission for shorter lasers (L(approximately-less-than)65 μm). The transition from longitudinal to vertical laser operation as a function of cavity length, L, is demonstrated. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5436-5440 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The problems associated with constructing AlxGa1−xAs native-oxide-based distributed Bragg reflectors (DBRs) for vertical cavity surface emitting lasers are investigated. Reflection and stability measurements are performed on structures with central λ/2 cavities (λ∼980 nm) of GaAs surrounded by two periods of native-oxide-based DBRs on the top and 2.5 periods on the bottom. Prior to crystal oxidation (H2O vapor+N2, 430 °C) a period of the DBRs consists of a ∼λ/4 optically thick layer of GaAs and a thicker (oxidation) layer of AlxGa1−xAs (x=0.95, 0.96, 0.97, 0.98, 1.00) surrounded by thinner (∼100 Å) buffer layers that are AlyGa1−yAs (y=0, 0.25, 0.50, 0.65, 0.070, 0.75, 0.80, 0.85). The DBRs are formed after oxidation of the high Al composition AlxGa1−xAs layers, and to some extent the AlyGa1−yAs buffer layers, forming a ∼λ/4 optically thick layer of the native oxide. For comparison, more complicated DBRs are created by oxidizing superlattice layers. It is found that the AlxGa1−xAs composition, x, of the oxidation layer, choice of oxidizing or nonoxidizing AlyGa1−yAs buffer layers (y), oxidation parameters, and post-processing parameters determine the DBR quality and stability, as well as the possibility of reoxidation. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 926-928 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vertical-cavity surface-emitting lasers (VCSELs) and resonant-cavity light-emitting diodes (RCLEDs) are demonstrated with high index contrast distributed Bragg reflectors (DBRs) on either side of a λ-thickness cavity (λ∼980 nm). The devices, with tunnel contact junctions making possible lateral electron current excitation, have a lower 6.5 period native-oxide-based AlxOy/GaAs DBR and an upper reflector that is either a 2–4 period AlxOy/GaAs DBR, a 1–2 period SiO2/ZnSe DBR, a λ/4-thickness layer of AlxOy (antireflecting), or no mirror at all. The AlxOy/GaAs DBRs and a buried-oxide-defined current aperture are formed by selective oxidation of the high Al composition AlxGa1−xAs layers. Device characteristics are observed as a function of the upper DBR periodicity (reflectivity). Devices with upper reflectivities of R(approximately-greater-than)99% operate as VCSELs while those with less reflectivity R(approximately-less-than)96% operate as RCLEDs, some with external differential quantum efficiencies as high as η∼27% and narrow spectral emission (Δλ∼50 Å). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on high-power AlGaInN flip-chip light-emitting diodes (FCLEDs). The FCLED is "flipped-over" or inverted compared to conventional AlGaInN light-emitting diodes (LEDs), and light is extracted through the transparent sapphire substrate. This avoids light absorption from the semitransparent metal contact in conventional epitaxial-up designs. The power FCLED has a large emitting area (∼0.70 mm2) and an optimized contacting scheme allowing high current (200–1000 mA, J∼30–143 A/cm2) operation with low forward voltages (∼2.8 V at 200 mA), and therefore higher power conversion ("wall-plug") efficiencies. The improved extraction efficiency of the FCLED provides 1.6 times more light compared to top-emitting power LEDs and ten times more light than conventional small-area (∼0.07 mm2) LEDs. FCLEDs in the blue wavelength regime (∼435 nm peak) exhibit ∼21% external quantum efficiency and ∼20% wall-plug efficiency at 200 mA and with record light output powers of 400 mW at 1.0 A. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2286-2288 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlxGa1−xAs-GaAs-InyGa1−yAs quantum well heterostructure (QWH) lasers with p+-n+ GaAs–InyGa1−yAs reverse-biased tunnel junctions (hole sources) located in the upper cladding of standard lasers and in oxide-defined cavities (requiring lateral bias currents) are demonstrated. The tunnel junctions, introduced to aid lateral current spreading, are grown at different distances from the waveguide active region in a standard QWH structure to determine first the effect of heavily doped tunnel layers on laser threshold currents. Other QWH laser crystals are oxidized to form oxide-aperture devices with, in addition, either a top confining oxide or a top and bottom oxide confining layer. Hole injection is provided between the oxide layers with the aid of the tunnel contact junction and lateral electron current. The buried tunnel contact junction is shown to be an effective method to make possible hole injection via a lateral electron current, with only a modest increase (a small penalty) in voltage drop and series resistance compared to standard devices. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1119-1121 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on the laser operation of photoexcited active hexagonal photonic lattices consisting of a GaAs–AlAs superlattice slab waveguide patterned with Zn-disordered AlGaAs posts that are converted to oxide. The semiconductor-oxide-post photonic lattice structure lases without the benefit of cleaved edges or other reflecting interfaces owing to strong local optical feedback provided by the high refractive index contrast between oxide posts and the active GaAs–AlAs superlattice. As the pump area is increased at constant pump power, the threshold intensity decreases as higher Q modes in an effectively larger cavity are excited. Similar hexagonal photonic lattices with nonoxidized posts (disordered AlGaAs posts) operate as lasers, but only with the assistance of cleaved edges and by shifting to longer wavelength. The oxide post photonic lattice is compatible with current-driven photonic lattice lasers or active filters.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2742-2744 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vertical cavity surface emitting lasers (VCSELs) are demonstrated with high-index-contrast native-oxide-based (AlxOy) distributed Bragg reflectors (DBRs) on both sides of a "2λ" cavity, thus creating a compact (thin, ∼2.8 μm) laser structure. Selective oxidation of high Al composition AlxGa1−xAs layers yields a structure with a four period upper AlxOy/GaAs DBR, a 5.5 period lower AlxOy/GaAs DBR, and a buried oxide current aperture. A reverse-biased tunnel contact junction provides hole injection via lateral electron current between the upper DBR and the oxide aperture layer. These VCSELs operate with submilliampere thresholds, high spontaneous efficiencies, and excellent polarization control. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3468-3470 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vertical cavity surface emitting lasers (VCSELs) are demonstrated with reverse-biased tunnel contact junctions allowing low-loss lateral electron current to support hole injection. A compact hybrid vertical cavity is employed consisting of a lower 6.5 period AlxOy/GaAs distributed Bragg reflector (DBR) formed by selective oxidation of high Al composition AlxGa1−xAs, and an electron-beam deposited 5 period SiO2/Si upper DBR. The cavity (active region) is defined also by selectively oxidizing a current-confining aperture. Lateral electron current drives a tunnel contact junction providing hole injection underneath the upper DBR through the oxide-defined current aperture. The p-type crystal in the VCSEL is reduced to a minimum, thus reducing resistive loss and device voltage. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented demonstrating double injection and negative resistance in stripe-geometry oxide-aperture AlyGa1−yAs–GaAs–InxGa1−xAs quantum well heterostructure lasers. The buried oxide laser structures are defined, in current and cavity, by laterally oxidizing the higher Al composition upper and lower cladding layers from a mesa edge (a ridge), thus, forming a narrow oxide-defined buried aperture (∼2μm). Post fabrication annealing (425 °C in N2) removes the negative resistance, indicating that the crystal growth and oxidation processes introduce products such as H and OH in the active region that compensate the dopants. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 1997-12-15
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...