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  • 1
    Electronic Resource
    Electronic Resource
    Spontaneous formation of Al rich and Ga rich AlxGa1−xAs/AlyGa1−yAs superlattice and strong enhancement of optical properties (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1921-1923 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Long range composition ordering and spontaneous formation of Al rich and Ga rich AlxGa1−xAs/AlyGa1−yAs superlattice were demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in a 280 A(ring) Al0.4GaAs quantum well laser diode heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates. On the contrary, none of above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. More evidence is shown in the (111)B Al0.7GaAs barriers which were disordered due to a high growth temperature and did not show any superstructure. 10 K photoluminescence was shown with 32 meV redshift and a 12-times peak intensity enhancement in (111)B orientation. © 1994 American Institue of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112817
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  • 2
    Electronic Resource
    Electronic Resource
    Optical and structural properties of spontaneously formed long-range compositional modulation in (111)A and (111)B AlGaAs (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8669-8674 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the spontaneously formed long-range Al-rich and Ga-rich AlxGa1−xAs/AlyGa1−yAs superlattices in both (111)A and (111)B AlGaAs during epitaxial growth. The spontaneously formed compositional modulation has been investigated by cross-sectional transmission electron microscopy in AlxGa1−xAs (x=0.3–0.4) grown on (111)A and (111)B GaAs substrates at 600–700 °C. In contrast, similar superstructures are not observed in layers simultaneously grown on (100) substrates. The observed structural compositional modulation is closely related to the large peak energy redshift and peak intensity enhancement in 15 K photoluminescence (PL) of samples grown on both (111)A and (111)B orientations to those on (100). The respective redshifts of PL peak energy for (111)A and (111)B Al0.27Ga0.73As to that of (100) are 137 and 45 meV, while the PL integrated intensity enhancement to (100) amounts to 200 and 2000 times, respectively. The effect of compositional modulation is reduced with the increasing growth temperatures as shown in the considerably less compositionally modulated (111)A and (111)B Al0.40Ga0.60As grown at 700 °C. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362492
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  • 3
    Electronic Resource
    Electronic Resource
    Surface and bulk leakage currents in transverse junction stripe lasers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1081-1090 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents two ways to reduce leakage currents in transverse junction stripe (TJS) lasers: by reducing surface leakage current and by reducing bulk leakage current. The surface leakage is reduced by treatment with (NH4)2S, while the bulk leakage current is reduced by isoelectronic doping with indium. We report the first detailed experimental investigation on the effect of the chemical treatments on the electrical characteristics and laser thresholds of TJS lasers. Surface treatments of (NH4)2S are demonstrated that reduce surface leakage currents in current injection lasers. After the chemical treatments, a 20-fold reduction in current has been achieved with GaAs/AlGaAs lattice-matched multiple-quantum-well TJS lasers. The laser thresholds of lattice-matched TJS lasers are reduced by 12 mA (or 16%) after the chemical treatments. In addition, InGaAs-GaAs-AlGaAs strained-layer single-quantum-well lasers are treated chemically and a reduction in the laser threshold (10 mA or 14%) is observed. The surface treatments are still effective after 7 days. We also report the first experimental investigation on the effect of isoelectronic In doping on the current-voltage characteristics of Zn-diffused lateral p-n junctions. The trap density in an In-doped AlGaAs layer is reduced by more than one order of magnitude compared to that in an AlGaAs layer without In doping. Bulk leakage currents (shunting currents) in TJS lasers can be reduced by using isoelectronic In doping, which should reduce threshold currents and improve the temperature dependence of TJS lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347375
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  • 4
    Electronic Resource
    Electronic Resource
    InGaAs-GaAs-AlGaAs strained-layer laser with heavy silicon doping (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 568-573 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence characteristics of uniformly silicon- and beryllium-doped pseudomorphic InGaAs-GaAs-AlGaAs single- and multiple-quantum-well heterostructures grown by molecular-beam epitaxy are studied. Red shifts in the photoluminescence peaks are obtained from uniformly silicon-doped single-quantum-well samples with respect to undoped samples. Uniformly beryllium-doped InGaAs-GaAs multiple quantum wells totally intermix during materials growth. Also, the effect on laser performance (laser thresholds and emission spectra) by silicon doping is demonstrated with an InGaAs-GaAs-AlGaAs strained-layer laser (grown by molecular-beam epitaxy) with a heavily silicon-doped quantum well. The low laser threshold, kink in light versus current, shift in emission wavelength, and two emission peaks are observed, and these characteristics are believed to be due to heavy silicon doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349657
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  • 5
    Electronic Resource
    Electronic Resource
    Negative differential resistance in a strained-layer quantum-well structure with a bound state (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3453-3456 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained-layer resonant tunneling structures of pseudomorphic GaAs-AlAs-In0.09Ga0.91As-AlAs-GaAs are studied both experimentally and with a simple quantum mechanical model. The energy spectrum of the unbiased structure includes the usual resonant states and also bound states due to the narrow-band gap InGaAs well. Strong tunneling (and negative differential resistance) are observed for the resonant states. We observe for the first time tunneling associated with a "bound-state'' energy level which result in a zero differential conductance feature. Qualitative agreement between the experimental and calculated results are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339315
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of threading dislocations on electron transport in In0.24Ga0.76N/GaN multiple quantum wells (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2167-2169 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of threading dislocations on electron transport in In0.24Ga0.76N/GaN multiple quantum wells has been studied by using transmission electron microscopy (TEM) and van der Pauw Hall effect measurements. From the cross-sectional TEM imaging, we observed the threading dislocations which "screw" through the multiple In0.24Ga0.76N/GaN quantum well. From the Hall effect measurement, we found that the Hall mobility decreases as the temperature decreases (μ∼T3/2) due to the threading dislocation scattering, and the Hall carrier concentration shows a transition from conduction-band transport to localized-state-hopping transport. The thermal activation energy of the residual donor level (probably Si) is about 20.2 meV. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123789
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  • 7
    Electronic Resource
    Electronic Resource
    Piezoelectric effect on Al0.35−δInδGa0.65N/GaN heterostructures (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2684-2686 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al0.35−δInδGa0.65N/GaN heterostructures have been studied by using transmission electron microscopy, photoluminescence, and Shubnikov–de Haas (SdH) measurements. In the sample of δ〈0.01%, two SdH oscillations beat each other due to the population of the lowest two subbands. The carrier concentrations of these two subbands are 1.398 and 1.248×1013 cm−2 and the electric field at the interface is reduced to 2.19×104 V/cm, which is one order of magnitude smaller than that of Al0.35Ga0.65N/GaN heterostructure. We suggest that a small fraction of In atoms in the Al0.35−δInδGa0.65N can be used as a tuning parameter to control the strain and the piezoelectric field at the interface. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1469209
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  • 8
    Electronic Resource
    Electronic Resource
    Stimulated emission in ultrathin (20 A(ring)) AlxGa1−xAs-GaAs single quantum well heterostructures (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1853-1855 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spontaneous and stimulated emission spectra from a series of AlxGa1−xAs-GaAs single quantum well heterostructures are demonstrated for well widths as thin as 20 A(ring). These undoped samples, grown by molecular beam epitaxy, are the thinnest single quantum wells ever reported to support stimulated emission. Laser thresholds are generally quite low (1.2 kW/cm2) despite the fact that the single well is undoped and of dimensions which were previously thought to be too small to effectively collect excess carriers (Lz(very-much-less-than)scattering path length). A simple model based on the spatial extent of the wave function, rather than the well width, is proposed to explain the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99619
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  • 9
    Electronic Resource
    Electronic Resource
    Continuous room-temperature operation of an InGaAs-GaAs-AlGaAs strained-layer laser (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 215-217 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first continuous wave room-temperature InGaAs-GaAs-AlGaAs strained-layer semiconductor laser diode grown by molecular beam epitaxy. The laser is a multiple quantum well transverse junction stripe laser with a lateral heterojunction fabricated by zinc diffusion enhanced compositional disordering. The low-threshold (20 mA) and single-mode performance of the laser demonstrates that a high-quality lateral p+-p-n junction and lateral heterobarrier can be formed by zinc diffusion compositional disordering of a strained-layer InGaAs-GaAs-AlGaAs quantum well heterostructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98479
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  • 10
    Electronic Resource
    Electronic Resource
    Stimulated emission from monolayer-thick AlxGa1−xAs-GaAs single quantum well heterostructures (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 626-628 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Stimulated emission from a clearly defined quantum well transition has been observed from single quantum wells as thin as two monolayers (ML, 1 ML=2.83 A(ring)). These results are unexpected since previous experimental and theoretical work has indicated that if the well width Lz is smaller than the scattering path length of electrons or holes, carrier collection becomes inefficient and the quantum well cannot support stimulated emission. Laser thresholds of these separate confinement, single quantum well samples are quite low, despite the fact that these ultrathin quantum wells are undoped and do not have graded band-gap confining layers. These unexpected results can be explained in terms of the spatial extent of the wave function rather than the well thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102718
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