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  • 1
    Electronic Resource
    Electronic Resource
    Self-aligned Si-Zn diffusion into GaAs and AlGaAs (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1855-1858 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A practical technology for self-aligned Si-Zn diffusion into GaAs and AlGaAs has been developed. It is found that the use of a Si film alone for self-aligned Si-Zn diffusion is subject to serious problems of morphology degradation and doping contamination during the process of the Si diffusion. A procedure combining the use of a SiO2 film as an encapsulant with a sputtered Si film as source for Si diffusion and mask for Zn diffusion is investigated in detail. Optimum thicknesses of the Si and SiO2 films are determined to be 180 and 550 A(ring), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341761
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  • 2
    Electronic Resource
    Electronic Resource
    Wide-bandwidth, high-efficiency reflection modulators using an unbalanced Fabry–Perot structure (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1946-1948 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A normally-on electroabsorptive multiple quantum well asymmetric Fabry–Perot reflection modulator with an on/off ratio of 22, insertion loss of 3.7 dB, and optical bandwidth of 3.4 nm for a voltage swing of 11 V has been measured. The trade-off between low insertion loss and high contrast in such devices will be discussed in the present letter and is shown to be due to the relative placement in wavelength between the Fabry–Perot resonant mode and the heavy hole exciton position in the multiple quantum well active region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102172
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of quantum-confined Stark effect in interdiffused and abrupt GaAs/AlGaAs quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2526-2528 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photocurrent measurements at room temperature have been carried out on thermally interdiffused GaAs/AlGaAs multiple quantum well structures. Although quite comparable, the Stark shift (quantum-confined Stark effect) in the disordered well is smaller than in the as-grown well. These measurements are consistent with calculations of the electron–heavy hole displacement versus electric field for infinite and square well models for the as-grown well, as well as parabolic and error function well models for the disordered well. We observe that this displacement increases faster for the wells with graded barriers which fit the experimental disordered well. Consequently, the exciton binding energy is smaller, which is consistent with the reduction of the Stark shift revealed by the photocurrent measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101971
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  • 4
    Electronic Resource
    Electronic Resource
    Spontaneous growth of coherent tilted superlattice on vicinal (100) GaAs substrates (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1690-1692 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Periodic Al composition modulations have been observed to occur spontaneously during molecular beam epitaxy of AlGaAs on vicinal (100) substrates. The formation of the spontaneous Al modulation requires (a) the migration-enhanced epitaxy deposition and (b) one monolayer deposition of Al and Ga atoms per cycle, hence, the denomination of coherent tilted superlattice (C-TSL). Cross-sectional transmission electron microscopy clearly shows that the C-TSL has the periodicity of the surface steps. We also show that the Al-rich regions of the C-TSL form at the bottom of steps before the As flux is established. These results indicate that growth kinetics dominates the C-TSL formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101304
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of geometric effects for the guide/antiguide intensity modulator (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4455-4457 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The characteristics of geometric dimensions, such as the modulation length L, the central guide width W, and the gap G between the central guide and antiguide regions for the performance of the guide/antiguide intensity modulator have been examined. Both theoretical predictions and experimental measurements are reported here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352186
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  • 7
    Electronic Resource
    Electronic Resource
    Tight-binding analysis on exciton binding energy in field-induced Stark-localized superlattices (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2002-2004 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use a variational calculation to study the excitonic behavior in a multiwell system. With several approximations, the exciton binding energy problem is reduced to a simple form, and the exciton binding energy is found to vary quadratically with the electron wave function confinement factor in the well with localized holes. This simple model is applied to explain quantitatively the localized exciton binding energy in a Stark-localized superlattice. It is found that a 50% electron wave function confinement factor is necessary to provide a strong excitonic effect in a multiwell system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102146
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of layer thickness variations on the performance of asymmetric Fabry–Perot reflection modulators (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 855-860 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a study of the effect of the active cavity layer thickness variations on the operating characteristics of normally on low voltage high performance asymmetric Fabry–Perot modulators. For a modulator consisting of 25.5 periods of 100 A(ring) GaAs quantum wells confined by 45 A(ring) (GaAs/AlAs) short period superlattices with 5 pairs and 20.5 pairs of top and bottom quarter-wave stacks, respectively, and assuming only layer thickness variation caused by Ga flux nonuniformity, the shift of the Fabry–Perot mode wavelength with respect to the fractional change of GaAs thickness inside the active cavity is ∼6 times that of the quantum well heavy hole exciton. This affects the relative distance between the wavelengths of the quantum well exciton and the Fabry–Perot resonance, and hence the performance of the modulators. Also, the tolerable percentage change of the Fabry–Perot mode wavelength should be less than 0.13% in order that such modulator arrays have at least 10:1 contrast ratios at a fixed optimum operating wavelength. This defines the epitaxial growth tolerance and precision with which we can obtain a desired operating wavelength, and the uniformity requirement on the two-dimensional arrays of such kind of modulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351758
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  • 9
    Electronic Resource
    Electronic Resource
    Effective band gap inhomogeneity and piezoelectric field in InGaN/GaN multiquantum well structures (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2006-2008 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The emission mechanisms of strained InxGa1−xN quantum wells (QWs) were shown to vary depending on the well thickness, L, and x. The absorption edge was modulated by the quantum confined Stark effect and quantum confined Franz-Keldysh effect (QCFK) for the wells, in which, for the first approximation, the product of the piezoelectric field, FPZ, and L exceed the valence band discontinuity, ΔEV. In this case, holes are confined in the triangular potential well formed at one side of the well producing the apparent Stokes-like shift. Under the condition that FPZ×L exceeds the conduction band discontinuity ΔEC, the electron-hole pair is confined at opposite sides of the well. The QCFK further modulated the emission energy for the wells with L greater than the three dimensional free exciton Bohr radius aB. On the other hand, effective in-plane localization of carriers in quantum disk size potential minima, which are produced by nonrandom alloy compositional fluctuation enhanced by the large bowing parameter and FPZ, produces a confined electron-hole pair whose wave functions are still overlapped (quantized excitons) provided that L〈aB. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122350
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  • 10
    Electronic Resource
    Electronic Resource
    Technique for integration of vertical cavity lasers and resonant photodetectors (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1-3 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate a design that allows fabrication of substrate input/output resonant-cavity photodetectors and vertical cavity lasers (VCLs) on the same substrate without regrowth. By selectively oxidizing a few layers in the bottom mirror the as-grown 80% reflectivity mirror, used as the input mirror for the detector, is converted to a 99.3% reflectivity mirror allowing fabrication of VCLs from the same epitaxial material. Since these two reflectivities are uncorrelated, the detectors and VCLs can be individually designed. Despite the change in refractive index from ∼3 to ∼1.6 in the oxidized layers, the structure can be designed to have nearly the same resonance wavelength for both the detectors and VCLs. Using this design strategy, we have successfully fabricated high-performance resonant photodetectors and VCLs from the same epitaxial material. The photodetectors have an absorption of 56% and an optical bandwidth of 5.9 nm, in good agreement with theory. Small diameter, single-mode VCLs have threshold currents as low as 180 μA with 33% slope efficiencies while multimode devices have slope efficiencies exceeding 60% with less than 500 μA threshold currents. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122951
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