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  • 1
    Electronic Resource
    Electronic Resource
    Measurement and calculation of spontaneous recombination current and optical gain in GaAs-AlGaAs quantum-well structures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1144-1156 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental determinations have been made of the peak optical gain as a function of spontaneous recombination current density for GaAs quantum wells of width 25 and 58 A(ring) bounded by AlGaAs barriers. These data were obtained from measurements of spontaneous emission spectra, observed through narrow windows in the 50-μm-wide contact stripes of oxide isolated lasers, using only a single reference value of the optical absorption coefficient above the band edge to calibrate the measurements in absolute units. These results are in good agreement with gain-current curves calculated using a model which includes unintentional monolayer well width fluctuations, band-gap narrowing and intraband carrier-carrier scattering. The characteristic intraband scattering time is calculated from first principles as a function of electron energy and carrier density on the basis of a 2-dimensional Auger-type process. This lifetime gives a much better representation of our observed spontaneous spectra than a lifetime which is simply dependent upon carrier density. The comparison between experiment and model calculation involves no adjustable parameters. For the 58-A(ring)-wide wells there is a difference between the experimental and calculated gain-current curves at low values of gain. We show that this is a consequence of applying the Einstein relations to a broadened spectrum in the process of deriving the gain from the observed spontaneous emission spectrum. A direct comparison of the shapes of experimental and calculated spontaneous emission spectra at several injection levels provides a more rigorous, yet equally valid, verification of the computer model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349622
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of the lasing wavelength of InGaAs quantum dot lasers (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4859-4861 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We observe that the emission wavelength of edge-emitting InGaAs quantum dot lasers has a much weaker temperature dependence (0.6 Å K−1) than equivalent quantum well devices (3 Å K−1). Measured gain and absorption spectra show that the gain peak wavelength due to dot states is almost independent of temperature for a given value of peak gain whereas the absorption edge shifts at a rate of about 2 Å K−1. Above 100 K the occupancy of dot states can be described by Fermi functions and on this basis we find that the measured gain and absorption spectra are in excellent quantitative agreement. Although the band edge energy reduces with increasing temperature, this analysis shows that the energy distribution of dot states matches the evolution of the Fermi functions such as to leave the quasi Fermi level separation and the wavelength of the gain peak unchanged as a function of temperature for a given value of peak gain. This energy distribution is a consequence of the dot size distribution so the match to the Fermi functions is probably fortuitous. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1402666
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  • 3
    Electronic Resource
    Electronic Resource
    The temperature dependence of threshold current of chemical beam epitaxy grown InGaAs–InP lasers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1804-1807 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature dependence of threshold current between 130 and 310 K of 1.65 μm In0.53Ga0.47As–InP bulk lasers grown by chemical beam epitaxy has been measured. Comparison with a calculation of the spontaneous recombination current at threshold allows one to determine the proportion of current loss over this temperature range. It is found that the loss can be described using an Auger recombination component of the form Rauger=C'n3 exp(−Ea/kBT) where n is the carrier population density in the undoped active region. The activation energy Ea is found to be 39±5 meV which is in excellent agreement with the theoretical value for the conduction to heavy hole band/split-off to heavy hole band Auger process. The values obtained for the Auger coefficient C over the temperature range are in close agreement with published values obtained by time resolved photoluminescence. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360212
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  • 4
    Electronic Resource
    Electronic Resource
    Optical and electrical properties of selectively delta-doped strained InxGa1−xAs/GaAs quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2627-2632 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report here an investigation of selectively delta-doped strained InGaAs/GaAs quantum wells. Electronic structures of the systems were calculated by self-consistently solving the Schrödinger and Poisson equations and the calculations revealed a systematic variation of the band structure as the delta sheet moved away from the center of the well to the edge and finally to the barrier. The results were found to be in agreement with our photoluminescence (PL) measurements. For center-doped samples, band-gap renormalization was found to be strong from the PL data, and our realistic random-phase approximation calculation for the heavily doped sample is in excellent agreement with the PL data. The radiative lifetimes were measured to be around 450 ps for all the samples, and surprisingly they vary very little from sample to sample although the wave-function overlap was considerably different for some samples. We also report Shubnikov–de Haas (SdH) measurements on the two barrier doped cases. For the heavily doped sample (A12132), two oscillation signals were detected and they were identified as two upper subbands. The measured electron densities were in very good agreement with the self-consistent calculation. Illumination did not make any difference to the measured densities. For the low-doped sample (A12025), however, the measured electron density before illumination is much smaller than the calculated, and illumination was found to make a large difference. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361133
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  • 5
    Electronic Resource
    Electronic Resource
    On the determination of internal optical mode loss of semiconductor lasers (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2365-2367 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Use is made of a numerical simulation of the light—current characteristic to examine the errors which may arise in the determination of the optical mode loss (αi) from the cavity length dependence of the external differential efficiency (ηextd). In particular, we focus on the effects of incomplete Fermi level pinning and carrier leakage, and show that αi can only be determined correctly if ηextd is determined under conditions where it is invariant both with current level and temperature. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118875
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  • 6
    Electronic Resource
    Electronic Resource
    Threshold current temperature dependence of GaInP/(AlyGa1−y)InP 670 nm quantum well lasers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1265-1267 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature dependence of threshold current of (AlyGa1−y)InP/GaInP quantum well lasers (y=0.3, 0.4, and 0.5) has been investigated and used to characterize thermally activated loss mechanisms above room temperature. We show good agreement between activation energies measured by Arrhenius analysis and those expected for the loss of electrons from the well to the X-conduction band minima in the barrier. Our analysis uses measured band gaps of the actual structures, avoiding assumptions about the alloy compositions, spontaneous emission data to subtract radiative and other direct gap processes, and recent band gap data for this alloy system. This provides convincing experimental confirmation of the loss of electrons from the indirect minima as the preferred process causing the rise in current at high temperature in these lasers. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114392
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  • 7
    Electronic Resource
    Electronic Resource
    Spontaneous recombination current in InGaAs/GaAs quantum well lasers (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1482-1484 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the intrinsic factors which determine the threshold current and its temperature dependence in 160-A(ring)-wide In0.2Ga0.8As single well quantum lasers with GaAs barriers, grown by molecular beam epitaxy on GaAs substrates. By measuring the relative temperature dependence of the spontaneous emission intensity at threshold we show that radiative transitions between higher order (n=2,3) electron and heavy hole subbands make a significant contribution to the threshold current and its temperature sensitivity, even in devices where the laser transitions are between n=1 subbands. These higher transitions will also influence the dependence of threshold current and its temperature sensitivity on well width.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103370
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  • 8
    Electronic Resource
    Electronic Resource
    Recombination processes in quantum well lasers with superlattice barriers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2380-2382 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spontaneous emission spectra from GaAs quantum well lasers grown by molecular beam epitaxy show that the radiative recombination rate in (AlAs)(GaAs) superlattice barriers is greater than in alloy barriers of the same average composition (x=0.25) due to reduction in effective gap by superlattice effects. Measurements of emission spectra as functions of temperature show that these radiative processes account for a significant part of the temperature variation of the threshold current and we estimate that the nonradiative lifetime in the superlattice barriers is an order of magnitude longer than in alloy barriers grown under similar conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102023
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  • 9
    Electronic Resource
    Electronic Resource
    Temperature dependence of spontaneous emission in GaAs-AlGaAs quantum well lasers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1167-1169 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using quantum well laser devices with a window in the p-type contact, we have measured the relative change of spontaneous emission intensity at threshold with temperature for 58-A(ring)-wide GaAs wells. Over the range 250–340 K the data are in good agreement with the linear relation obtained from a gain-current calculation which includes transition broadening. This linear behavior contrasts with the stronger temperature dependence of the total measured threshold current of the same devices which includes nonradiative barrier recombination processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101686
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  • 10
    Electronic Resource
    Electronic Resource
    Observations of barrier recombination in GaAs-AlGaAs quantum well structures (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2218-2220 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using laser structures with a window in the contact stripe, we have observed recombination from the wells and barrier regions of GaAs-AlGaAs quantum well lasers. The magnitude of the ratio of emission intensities from the barrier and the well, and the dependence of this ratio upon injection current, are in good agreement with a calculation in which the carrier populations in well and barrier are in thermal equilibrium at the lattice temperature (300 K).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101129
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