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  • 1
    Electronic Resource
    Electronic Resource
    Built-in biaxial strain dependence of Γ-X transport in GaAs/InxAl1−xAs/GaAs pseudomorphic heterojunction barriers (x=0, 0.03, and 0.06) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7907-7914 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of built-in biaxial strain on Γ-X transport in n-GaAs/i-InxAl1−xAs/n-GaAs pseudomorphic single-barrier structures (x=0, 0.03, and 0.06) are studied by measuring temperature-dependent I-V characteristics. For the accurate characterization of electron transport across each barrier, a self-consistent numerical model is used to analyze the experimental results. For each structure, the four barrier parameters defined from the thermionic-field-emission theory, the effective Richardson constant A*, the conduction-band offsets ΔEc1,2, and a tunneling mass mn* are extracted by calculating the theoretical I-V characteristics and fitting them to the experimental I-V-T data. The experimentally obtained X-point conduction-band shifts with the addition of indium are compared with the theoretical results calculated based on the model-solid theory. The results indicate that the addition of indium not only splits the degenerate X minima of the InxAl1−xAs barrier, but also shifts the relative barrier heights of both longitudinal and transverse X valleys due to the alloy-dependent band-structure modification. The comparison between the experimental and theoretical results illustrates that the transverse X valleys are the main conduction channel for the Γ-X transport across InxAl1−xAs pseudomorphic barriers. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357901
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  • 2
    Electronic Resource
    Electronic Resource
    Novel reflectance modulator employing an InGaAs/AlGaAs strained-layer superlattice Fabry–Perot cavity with unstrained InGaAs/InAlAs mirrors (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1608-1610 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a novel approach to optoelectronic devices by combining mechanically stable strained and unstrained epitaxial multilayers. We illustrate our approach with an optical reflectance modulator based on an asymmetric Fabry–Perot resonator designed to operate near 1.06 μm. The resonator is grown on a mechanically relaxed buffer of In0.11Ga0.89As deposited on a GaAs substrate. For mirrors, quarter-wave stacks of In0.11Ga0.89As and In0.1Al0.9As, lattice matched to the buffer, are used. The Fabry–Perot cavity consists of an In0.23Ga0.77As/Al0.35Ga0.65As strained-layer superlattice whose planar lattice constant also matches the buffer. Our first device operates at 1.04–1.05 μm depending on lateral position across the wafer. The insertion loss at resonance is less than 2 db and a fractional modulation of over 60% has been achieved with a 4 V bias swing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105140
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  • 3
    Electronic Resource
    Electronic Resource
    Optical scatter in epitaxial semiconductor multilayers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1360-1362 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of optical scatter in epitaxial semiconductor multilayer structures. The structures comprise quarter-wave layers of Al0.2Ga0.8As/AlAs and GaAs/AlAs grown by molecular beam epitaxy and Al0.2Ga0.8As/AlAs grown by metalorganic chemical vapor deposition to assess differences due to growth technique and layer composition. The bidirectional reflective distribution function (BRDF) is measured at a wavelength of 835 nm corresponding closely to the Bragg reflection condition of the multilayer. The BRDF measurement yields calculated values for the total integrated scatter and effective surface roughness. The former is in the range 7×10−4–5×10−3 while the latter is typically 3–16 A(ring) over the spatial frequency range 3×10 −2–1 μm−1. Both growth techniques yield comparable scatter loss on average, but there are significant differences in microscopic surface morphology, uniformity of scatter across the wafer, and lower limits of scatter. The measurements have significant implications for applications such as surface-emitting laser technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104308
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  • 4
    Electronic Resource
    Electronic Resource
    Coherent beams from high efficiency two-dimensional surface-emitting semiconductor laser arrays (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 890-892 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated and operated large two-dimensional (2D) arrays of phase-locked surface-emitting semiconductor lasers. The arrays were fabricated by reactive ion beam etching of epitaxial Fabry–Perot resonators comprising GaAs/AlGaAs quantum wells surrounded by AlAs-AlGaAs quarter-wave mirrors. Different arrays corresponding to different pixel size (2–5 μm) and spacing (1–2 μm) were produced to investigate evanescent coupling between pixels. The arrays were photopumped so that the array size could be conveniently varied from 1×1, 2×2,... up to 20×20. Except for the 1×1 which emits a circular pattern, all arrays exhibit a well-defined four-lobed far-field pattern in agreement with our theoretical analysis of the optical modes which predicts domination by the 2D out-of-phase eigenmode. As a consequence this pattern can be understood with simple Fraunhofer diffraction theory. The angular spread of the lobes, determined by the periodicity of the array elements, is 10° for the array with element size/spacing of 4/1 μm. The widths of the lobes are 6.7° for the 2×2 and narrow to 3.2° with increasing number of pixels in the array. The array exhibits a sharp onset for lasing, operation on a single longitudinal mode, and a linewidth which narrows to ∼1 A(ring) with increasing array size. The differential power efficiency is as high as 70%. These observations provide further impetus and guidance for the development of 2D laser diode arrays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104468
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  • 5
    Electronic Resource
    Electronic Resource
    Reflection mass spectrometry of As incorporation during GaAs molecular beam epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 288-290 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An apertured and cryoshrouded mass spectrometer, which measures line-of-sight molecular fluxes from the surface, has been incorporated into a GaAs molecular beam epitaxy system. The spectrometer is simple to implement, yet is a powerful real-time growth diagnostic. We have used the spectrometer to measure transient and steady-state As incorporation from As4 during bilayer-by-bilayer growth of GaAs. We find, interestingly, that (1) the incorporation coefficient does not oscillate significantly; (2) transient incorporation coefficients depend on surface reconstruction, and may be higher than 0.5 at high Ga fluxes; and (3) in the absence of a Ga flux, excess Ga on the surface need not imply an incorporation coefficient of 0.5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99916
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  • 6
    Electronic Resource
    Electronic Resource
    Unintentional indium incorporation in GaAs grown by molecular beam epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2321-2323 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have quantified unintentional indium incorporation in GaAs grown by molecular beam epitaxy in a variety of commercial systems. We find that the unintentional indium density in the epitaxial GaAs is more a function of mounting technique and prior machine history than of the manufacturer's design. The indium densities detected in the epitaxial GaAs for substrates that only partially obscure an indium-bearing mount are equal to levels reported to result in minimum defect densities and narrowest photoluminescence linewidths in In-doped GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103881
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  • 7
    Electronic Resource
    Electronic Resource
    Electric field dependent photocurrent and electroreflectance spectra of InGaAs/AlGaAs multiple strained quantum well structures (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1245-1247 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results on excitonic transitions and confinement at high electric fields from photocurrent and electroreflectance spectra of an In0.17Ga0.83As/Al0.3Ga0.7As strained quantum well structure fabricated into a Schottky barrier diode. Up to the highest field attained, 1.7×105 V/cm, we observe a well-defined exciton line at the band edge (in contrast to data on similar GaAs/Al0.3Ga0.7As structures), a feature important for potential optoelectronic applications. At low fields, "allowed'' (Δn=0) transitions dominate the photocurrent spectra, but with increasing field "forbidden'' transitions (allowed because of reduced symmetry and valence-band mixing) grow in intensity and eventually dominate the above-gap response. In the electroreflectance spectra, the forbidden transitions are relatively strong, even at low field. The allowed above-gap transitions nearly vanish at low temperature because of the small field dependence of the higher lying quantum well energy levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103498
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  • 8
    Electronic Resource
    Electronic Resource
    Role of substrate threading dislocation density in relaxation of highly strained InGaAs/GaAs quantum well structures (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1350-1352 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structures with highly strained InGaAs/GaAs single quantum wells have been grown on GaAs substrates with KOH etch pit densities from ∼1000 to ∼45 000 cm−2. These structures were characterized by photoluminescence microscopy and 77 K Hall measurements to determine the extent to which the substrate threading dislocation density affects the misfit dislocation density at the quantum well interfaces. For well thicknesses near or below the Matthews–Blakeslee critical thickness, similar results are obtained for substrates of different dislocation density. However, for metastable structures significantly above the critical thickness, the misfit dislocation density is a sensitive function of the substrate quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102511
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  • 9
    Electronic Resource
    Electronic Resource
    On-line determination of alloy composition during ternary III/V molecular beam epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 777-779 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a simple, new method for deducing surface alloy composition during ternary III/V molecular beam epitaxy. The method is based on on-line reflection mass spectrometry of the group V flux "reflected'' from the surface during momentary terminations of individual group III fluxes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101804
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  • 10
    Electronic Resource
    Electronic Resource
    Integrated injection-locked high-power cw diode laser arrays (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 531-533 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first integrated injection-locked high-power continuous-wave diode laser array with an on-chip independently controlled master laser. This device emits a near-diffraction-limited (0.5° full width at half maximum) single-lobed far-field emission beam at single-facet powers up to 125 mW. Also, by current tuning the emission wavelength of the master laser, we observe steering of the single-lobed emission over an angular range of 0.50° at a rate of −1.2×10−2 deg/mA. Our work demonstrates the feasibility of incorporating active optical injection and control in the structure of high-power diode laser devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101845
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