S. A. Chaparro

Tunneling carrier escape from InAs self-assembled quantum dots

Deep-level transient spectroscopy measurements in InAs quantum dots (QDs) grown in both n-GaAs and p-GaAs show that tunneling is an important mechanism of carrier escape from the dots. The doping level in the barrier strongly affects the tunneling emission rates, enabling or preventing the detection of a transient capacitance signal from a given QD level. The relative intensity of this signal acquired with different rate windows allows the estimation of tunneling emission energies.

Carrier recombination in 1.3μm GaAsSb∕GaAs quantum well lasers

In this letter the authors present a comprehensive study of the threshold current and its temperature dependence in GaAsSb-based quantum well edge-emitting lasers for emission at 1.3 mu m. It is found that at room temperature, the threshold current is dominated by nonradiative recombination accounting for more than 90% of the total threshold current density. From high hydrostatic pressure dependence measurements, a strong increase in threshold current with pressure is observed, suggesting that the nonradiative recombination process may be attributed to electron overflow into the GaAs/GaAsP barrier layers and, to a lesser extent, to Auger recombination. (c) 2006 American Institute of Physics.

Photoexcited carrier dynamics in aligned InAs/GaAs quantum dots grown on strain-relaxed InGaAs layers

Carrier dynamics in aligned InAs/GaAs quantum dots (QDs) grown on cross-hatched patterns induced by metastable InxGa1−xAs layers have been studiedby time-resolvedphotoluminescence. The low-temperature carrier lifetimes were found to be of the ord er of 100 –200 ps andd eterminedby carrier trapping andnonrad iative recombination. Comparisons with control “nonaligned” InAs QDs show remarkable di>erences in dependence of peak PL intensities on excitation power, and in PL decay times dependences on both temperature and excitation intensities. Possible origin of traps, which determine the carrier lifetimes, is discussed. ? 2003 Elsevier Science B.V. All rights reserved.

Cavity mode gain alignment in GaAsSb-based near-infrared vertical cavity lasers studied by spectroscopy and device measurements

We present a combination of spectroscopy and device measurements on GaAsSb/GaAs vertical-cavity surface-emitting laser (VCSEL) structures to determine the temperature at which the wavelength of the VCSEL cavity mode (CM) aligns with that of the quantum well (QW) ground-state transition (GST), and therefore the gain peak. We find that, despite the achievement of room temperature (RT) continuous wave lasing in VCSEL devices, the QW transition and the CM are actually slightly misaligned at this temperature; room temperature electroluminescence measurements from a cleaved edge of the VCSEL wafer indicate that the 300K QW GST energy is at 0.975 60.005eV, while the CM measured in the VCSEL surface reflectivity spectra is at 0.9805 60.0002eV. When the wafer sample is cooled, the CM and QW GST can be brought into alignment at 270 610K, as confirmed by temperature-dependent electro-modulated reflectance (ER) and edge-electroluminescence spectroscopic studies. This alignment temperature is further confirmed by comparing the temperature dependence of the emission energy of a fabricated VCSEL device with that of an edge-emitting laser structure with a nominally identical active region. The study suggests that for further device improvement, the room temperature CM and QW GST energies should be more closely matched and both designed to a smaller energy of about 0.95eV, somewhat closer to the 1.31lm target. The study amply demonstrates the usefulness of non-destructive ER characterisation techniques in VCSEL manufacturing with GaAsSb-based QWs. V C 2012 American Institute of Physics .[ http://dx.doi.org/10.1063/1.4744985]

Carrier recombination in 1.3 mu m GaAsSb/GaAs quantum well lasers

In this letter the authors present a comprehensive study of the threshold current and its temperature dependence in GaAsSb-based quantum well edge-emitting lasers for emission at 1.3 mu m. It is found that at room temperature, the threshold current is dominated by nonradiative recombination accounting for more than 90% of the total threshold current density. From high hydrostatic pressure dependence measurements, a strong increase in threshold current with pressure is observed, suggesting that the nonradiative recombination process may be attributed to electron overflow into the GaAs/GaAsP barrier layers and, to a lesser extent, to Auger recombination. (c) 2006 American Institute of Physics.

Carrier dynamics in spatially ordered InAs quantum dots

Spatial ordering of InAs quantum dots was attained by using misfit dislocations generated in a metastable InGaAs layer by means of thermal annealing. Influence of quantum dot positional ordering and dot proximity to dislocation arrays on carrier dynamics was studied by timeresolved photoluminescence. Substantially narrower inhomogeneous broadening from the ordered quantum dots was observed. Excitation intensity dependence of the photoluminescence intensity and carrier lifetime indicates stronger influence of nonradiative recombination for the ordered quantum dot structures. Numerical simulations allow estimating electron and hole capture rates from the quantum dots to traps located either at the quantum dot interfaces or in the vicinity of the quantum dots.

Carrier recombination in 1.3 μm GaAsSb/GaAs quantum well lasers

In this letter the authors present a comprehensive study of the threshold current and its temperature dependence in GaAsSb-based quantum well edge-emitting lasers for emission at 1.3 mu m. It is found that at room temperature, the threshold current is dominated by nonradiative recombination accounting for more than 90% of the total threshold current density. From high hydrostatic pressure dependence measurements, a strong increase in threshold current with pressure is observed, suggesting that the nonradiative recombination process may be attributed to electron overflow into the GaAs/GaAsP barrier layers and, to a lesser extent, to Auger recombination. (c) 2006 American Institute of Physics.

Carrier recombination in 1.3μmGaAsSb∕GaAs quantum well lasers

In this letter the authors present a comprehensive study of the threshold current and its temperature dependence in GaAsSb-based quantum well edge-emitting lasers for emission at 1.3 mu m. It is found that at room temperature, the threshold current is dominated by nonradiative recombination accounting for more than 90% of the total threshold current density. From high hydrostatic pressure dependence measurements, a strong increase in threshold current with pressure is observed, suggesting that the nonradiative recombination process may be attributed to electron overflow into the GaAs/GaAsP barrier layers and, to a lesser extent, to Auger recombination. (c) 2006 American Institute of Physics.

1.3-μm GaAsSb/GaAs VCSELs

Room-temperature continuous wave operation of Antimonide-based long wavelength VCSELs has been demonstrated, with 1.2mW power output at 1266nm, the highest figure reported so far using this material system. Single mode powers of 0.3mW at 10°C and 0.1mW at 70°C and side-mode suppression ratios up to 42dB have also been achieved. Preliminary reliability test results have shown so far that the devices can work normally without obvious degradation after stress testing at up to 125°C for thousands of hours.

Strain compensated GaAsP/GaAsSb/GaAs 1.3 /spl mu/m lasers grown on GaAs using MBE

Summary form only given. GaAs-based 1.3 /spl mu/m vertical cavity surface emitting lasers (VCSELs) are highly desirable for optical data communication. One of the most promising approaches is to use GaAsSb/GaAs quantum wells as the laser active region. Due to the large compressive strain necessary for the GaAsSb layer to reach 1.3 /spl mu/m, it can be prohibitive to use multiple QWs without compensating the strain. This paper reports GaAsSb/GaAs active layers sandwiched by tensilely strained GaAsP layers. The larger bandgap, of the GaAsP layers also provide stronger electron confinement.