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  • 1
    Electronic Resource
    Electronic Resource
    Pseudomorphic InGaAs/GaAs/AlGaAs mirrors for optical devices in the near-infrared 0.9–1.3 μm (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 380-383 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose using pseudomorphic multilayers of InGaAs, GaAs, and AlGaAs in optical mirrors for near-infrared devices including surface-emitting lasers, bistable optical devices, and optical modulators. We demonstrate the growth of a Fabry–Perot etalon by molecular-beam epitaxy and characterize it optically (reflectance, transmittance, photoluminescence) and structurally (scanning electron microscopy and dislocation imaging). We find the optical characteristics of the etalon as a whole and the individual quarter-wave layers indicate high structural quality for the mirrors. This is in spite of the fact that the lattice constant of the etalon structure is slightly relaxed from that of the GaAs substrate. These results indicate that pseudomorphic mirrors are useful candidates for integrated optical devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342553
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  • 2
    Electronic Resource
    Electronic Resource
    High-efficiency TEM00 continuous-wave (Al,Ga)As epitaxial surface-emitting lasers and effect of half-wave periodic gain (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1209-1211 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report room-temperature, continuous-wave (cw), photopumped operation of (Al,Ga)As surface-emitting lasers grown by molecular beam epitaxy. These monolithic semiconductor lasers comprise two multilayer semiconductor mirrors surrounding a layered active region. In the active region, GaAs quantum wells are spaced with half-wave periodicity to center on standing-wave maxima of the cavity optical field. By comparing threshold data for different lasers grown with and without half-wave periodicity, we observe the first experimental evidence for reduced cw lasing threshold (as low as 2×104 W/cm2 ) with periodic gain in an epitaxial surface-emitting laser. Up to 50 mW with high efficiency (35% total, 80% differential) and narrow spectral linewidth (2 A(ring)) have been measured. A very high quality beam with low divergence (2.5°) and circular TEM00 profile has been observed. All of these observations represent significant advances for surface-emitting laser technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100717
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  • 3
    Electronic Resource
    Electronic Resource
    Lasing threshold in quantum well surface-emitting lasers: Many-body effects and temperature dependence (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2698-2700 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The geometry of quantum well surface-emitting lasers has several important consequences. The ultrashort (∼1 μm) vertical cavity defines longitudinal modes with energy separation greater than the bandwidth of spectral gain. The optical confinement of these modes can approach unity. To achieve lasing, high carrier densities (∼1012 cm−2) in the quantum well are required. The confined carriers interact through enhanced many-body exchange which influences both the lasing wavelength and threshold characteristics. Indeed, the exchange interaction can facilitate the lasing process. We theoretically and experimentally study the role of the short cavity and exchange interaction on the cw lasing threshold as a function of temperature. In constrast to edge emitters, the lasing threshold in these surface emitters exhibits a well-defined minimum at a particular temperature. The temperature of the minimum can be designed by merely changing the active layer thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101928
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  • 4
    Electronic Resource
    Electronic Resource
    High-efficiency, continuous-wave, epitaxial surface-emitting laser with pseudomorphic InGaAs quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1397-1399 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first continuous-wave (cw) photopumped operation of surface-emitting lasers comprising pseudomorphic InGaAs quantum wells. The lasers were grown by molecular beam epitaxy and incorporate epitaxial quarter-wave AlAs/GaAs mirrors surrounding an active region. In the active region, 50 A(ring) InGaAs quantum wells are distributed with half-wave periodicity to center on cavity standing wave maxima. Lasing is observed from 78 to 250 K in the spectral range 920–950 nm, where the GaAs substrate is transparent. Thresholds were as low as 1.5×104 W/cm2, and overall (differential) output power efficiency was as high as 35% (85%) with up to 60 mW in a low divergence beam. Both periodic gain and biaxial compressive layer strain contribute to the reduced lasing threshold. The laser gain length is only 550 A(ring) (11 quantum wells). The possibility of surface-emitting lasing in single quantum wells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100678
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  • 5
    Electronic Resource
    Electronic Resource
    Electric field response of a semiconductor superlattice optical mirror from electroreflectance spectra (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1324-1326 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report low-field electroreflectance (ER) spectra of an all-semiconductor multilayer optical mirror structure. The structure, consisting of alternating blocks of AlAs/Al0.5Ga0.5 As and Al0.5Ga0.5As/GaAs multiple quantum well layers, was grown by molecular beam epitaxy without wafer rotation. Thickness variations across the wafer produce a position-dependent reflectance spectrum. The observed line shape of the band-edge exciton depends on its wavelength position relative to the mirror spectrum and cannot be explained by ordinary ER theory, due to the rapidly varying background mirror reflectance. Computer simulations, using the matrix method to calculate the reflectance for different layer thicknesses and exciton energies, agree qualitatively with the data. A strong enhancement in ER response is predicted near the minima in the mirror spectrum. This enhancement is important in electo-optic reflectance modulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101644
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  • 6
    Electronic Resource
    Electronic Resource
    Optical properties of two-dimensional photonic lattices fabricated as honeycomb nanostructures in compound semiconductors (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 687-689 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have experimentally studied two-dimensional photonic lattices, honeycomb nanostructures, fabricated by electron beam lithography with (Al,Ga)As materials. Surface normal optical properties were investigated by measuring reflectance to determine the effective index of refraction and lattice stability against degradation. Also, continuous wave and time-resolved luminescence spectroscopy was used to assess electron-hole recombination. Finally, light scattering was employed to study photon coupling and propagation through the lattice. These measurements show that the structures are stable, that nonradiative surface recombination is present, and that resonant coupling of light into/out of the lattice occurs at selected wavelengths satisfying a Bragg condition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111034
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of substrate misorientation on the structural properties of CdTe(111) grown by molecular beam epitaxy on GaAs(100) (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1747-1749 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: CdTe (111) layers were grown by molecular beam epitaxy on oriented and misoriented GaAs (100) substrates. The layers were characterized by x-ray diffraction and photoluminescence microscopy. The results indicate that the CdTe layers grown on GaAs (100) misoriented 2° towards the [110] direction had peaks with full width at half-maximum up to four times narrower than either of the other orientations tested. Only threading dislocations were visible on this orientation by photoluminescence microscopy. These results indicate that the structural quality of CdTe grown on GaAs can be significantly improved by the use of an appropriately misoriented substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99777
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  • 8
    Electronic Resource
    Electronic Resource
    Electrical and optical studies of dislocation filtering in InGaAs/GaAs strained-layer superlattices (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1098-1100 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report electrical transport and optical studies of the efficiency with which an In0.2Ga0.8As/GaAs strained-layer superlattice (SLS) can filter threading dislocations generated in a thick In0.1 Ga0.9 As layer grown on GaAs. The electrical studies, the first of their kind, rely on a novel test structure which allows electrical characterization of just the top portion of the SLS, with the bottom portion acting as the dislocation filter. For optical characterization we detect dislocations directly by photoluminescence microscopy. The electrical results show that ∼3–6 periods of filtering are needed to attain high mobilities. The photoluminescence microimages show a small density of dislocations near the top of an eight-period SLS but no dislocations for 11 or more periods. Filtering with In0.2Ga0.8As/GaAs SLS's is more effective than with GaAs0.8P0.2/GaAs SLS's, possibly because of larger interlayer differences in strain and elastic constants for the former.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100032
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  • 9
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy study of CdTe(111) grown on GaAs(100) by molecular-beam epitaxy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4114-4117 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used transmission electron microscopy to investigate CdTe(111) grown on GaAs(100) by molecular-beam epitaxy. The loop structure previously observed by photoluminescence microscopy has been identified as the boundary between twinned microcrystallites that extend from the CdTe/GaAs interface to the CdTe surface. When viewed along the growth axis, these boundaries between the columnar twins appear as loops and segments. Surface roughness of the GaAs substrate contributes to the initial growth of twinned material. This leads to competitive growth between the twins and the creation of the observed columnar twins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344971
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  • 10
    Electronic Resource
    Electronic Resource
    Threshold characteristics of epitaxial Al(Ga,As) surface-emitting lasers with integrated quarter-wave high reflectors (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6578-6580 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a study of threshold characteristics of as-grown surface-emitting lasers fabricated with molecular-beam epitaxy by the monolithic integration of two quarter-wave high reflectors (mirrors) of AlAs/Al0.4Ga0.6As surrounding an active spacer layer. The spacer was either a multiple quantum well of GaAs/Al0.4Ga0.6As (100 A(ring)/200 A(ring)) or GaAs. Several structures were grown corresponding to different mirror reflectance and different spacer thicknesses from ultrashort 0.9 to 10 μm. One of the structures was chemically etched to form a two-dimensional array of microlasers. All of the structures were photopumped at room temperature, and the lasing threshold was determined. Without any lateral confinement, the threshold irradiance was as low as 2×105 W/cm2. Near-field images of the light emitted slightly above threshold reveal several competing filaments. This competition broadens the lasing linewidth, but can be controlled by lateral confinement schemes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342033
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