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Sökning: swepub > Larsson Anders > Tidskriftsartikel > Sadeghi Mahdad 1964

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1.
  • Fu, Ying, et al. (författare)
  • Energy band structure and spectral gain characteristics of dilute-nitride zinc blende InGaNAs quantum wells embedded in GaAs and GaNAs barriers
  • 2006
  • Ingår i: Journal of Applied Physics. - 00218979. ; 100:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The spectral gain characteristics of dilute-nitride zinc blende InxGa1-xNyAs1-y quantum wells embedded in GaNy1As1-y1 barriers have been investigated experimentally and theoretically. Two samples, both with the gain peak at 1300 nm, were studied for comparison. One has a high nitrogen concentration in the quantum well with the surrounding barriers being pure GaAs. The other has a lower and uniform nitrogen concentration in the quantum well and the barriers (GaNAs barriers). Measurements show the redshift of the gain peak induced by the incorporation of nitrogen and difference in the spectral gain characteristics. The energy band structures and spectral gain characteristics are analyzed theoretically using the standard eight-band k center dot p theory. It is shown that the introduction of nitrogen atoms in the GaAs barriers reduces the barrier height for the central quantum well so that the energy sublevels in the conduction band becomes condensed. The condensation of the conduction-band energy sublevels reduces the peak gain and makes the gain spectrum narrower, in agreement with measurements.
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3.
  • Zhao, Huan, 1982-, et al. (författare)
  • Very Low Threshold Current Density 1.292 µm GaInNAs Triple Quantum Well Lasers
  • 2008
  • Ingår i: Electronics Letters. - 0013-5194. ; 44:7, s. 475-477
  • Tidskriftsartikel (refereegranskat)abstract
    • Very-low-threshold Ga0.62In0.38N 0.007As0.993/GaN0.011As0.989/GaAs triple quantum well (QW) lasers emitting at 1.29m are demonstrated. The laser structure was grown by molecular beam epitaxy after extensive optimisations of growth and in situ annealing conditions. As-cleaved broad-area lasers with a cavity length of 1mm under pulsed operation showed a record low-threshold current density of 400A/cm2 (∼130A/cm2/QW), a high differential efficiency of 0.32W/A/facet and a characteristic temperature of 94K in the temperature range 10 to 110°C. © The Institution of Engineering and Technology 2008.
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5.
  • Adolfsson, Göran, 1981-, et al. (författare)
  • Direct observation of lateral carrier diffusion in ridge waveguide InGaNAs lasers
  • 2009
  • Ingår i: IEEE Photonics Technology Letters. - 1041-1135. ; 21:134, s. 134-136
  • Tidskriftsartikel (refereegranskat)abstract
    • We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-mu m wavelength ridge waveguide InGaNAs quantum-well lasers using a scanning near-field optical microscopy technique. The measurements reveal the presence of significant lateral carrier diffusion which has a profound effect on the temperature dependence of the threshold current. This effect is frequently omitted when the characteristic temperature of the threshold current is considered.
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6.
  • Adolfsson, Göran, 1981-, et al. (författare)
  • Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3 um Double Quantum-Well GaInNAs/GaAs Lasers
  • 2008
  • Ingår i: IEEE Journal of Quantum Electronics. ; 44:7, s. 607-616
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an experimental and theoretical investigation of the temperature dependence of the threshold current for double quantum well GaInNAs–GaAs lasers in the temperature range 10 C–110 C. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide (RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T0)of 200 K up to a critical temperature (Tc), above which T0 is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above). Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates the threshold current for narrow RWG lasers.
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8.
  • Ferdos, Fariba, 1966-, et al. (författare)
  • Influence of a thin GaAs cap layer on structural and optical properties of InAs quantum dots
  • 2002
  • Ingår i: Applied Physics Letters. - 0003-6951. ; 81:7, s. 1195-7
  • Tidskriftsartikel (refereegranskat)abstract
    • In this letter we investigate the changes in the surface morphology and emission wavelength of InAs quantum dots (QDs) during initial GaAs encapsulation by atomic force microscopy and photoluminescence. The density (2.9×1010 cm-2) and height (7.9±0.4 nm) of the uncapped QDs decrease and saturate at 0.6×1010 cm-2 and 4 nm, respectively, after the deposition of 4 monolayers (MLs) of GaAs. A model for the evolution of surface morphology is proposed. Photoluminescence spectra of the surface dots show a wavelength shift from 1.58 to 1.22 ?m when the GaAs capping layer thickness increases from 0 to 8 MLs.
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9.
  • Ferdos, Fariba, 1966-, et al. (författare)
  • Influence of initial GaAs and AlAs cap layers on InAs quantum dots grown by molecular beam epitaxy
  • 2003
  • Ingår i: Journal of Crystal Growth. - 0022-0248. ; 251:1-4, s. 145-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Capping of InAs quantum dots (QDs) with AlAs or GaAs causes a significant change in the structural properties of the QDs. However, there is a basic difference between these two capping materials. The GaAs capping causes a dramatic reduction of the dot density and height. AlAs capping, on the other hand, results in a partly suppressed height reduction and a higher dot density.
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10.
  • Ferdos, Fariba, 1966-, et al. (författare)
  • Optimisation of MBE growth conditions for InAs quantum dots on (001) GaAs for 1.3 μm luminescence
  • 2001
  • Ingår i: Journal of Crystal Growth. - 0022-0248. ; 227-228, s. 1140-5
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a study of the optimised growth conditions for InAs quantum dots (QDs) grown on GaAs substrates by solid source molecular beam epitaxy (SSMBE). Growth conditions for best luminescence intensity and linewidth were found within narrow windows of substrate temperature (500-520°C) and nominal InAs layer thickness (3.3-3.7 monolayers). The emission wavelength of such InAs QDs capped by GaAs was around 1.24 ?m. However, this is redshifted to 1.3 ?m or more by capping the InAs QDs with a thin layer of InxGa1-xAs. The results show that both In content and thickness of the capping layer can be used to tune the emission wavelength. Atomic force microscopy images show that the surface recovers to two-dimensional when depositing In0.2Ga0.8As while remaining three-dimensional when depositing In0.4Ga0.6As.
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