Enhancement of activation energies of sharp photoluminescence lines for GaInNAs quantum wells due to quantum confinement (original) (raw)
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Journal of Applied Physics, 2003
We have investigated in-plane photovoltage ͑IPV͒ and photoluminescence ͑PL͒ in sequentially grown Ga 0.8 In 0.2 As/GaAs and Ga 0.8 In 0.2 N 0.015 As 0.985 /GaAs quantum wells. Temperature, excitation intensity, spectral and time dependent study of the IPV, arising from Fermi level fluctuations along the layers of the double quantum well structure, gives valuable information about the nonradiative centers and hence about the optical quality of the GaInNAs quantum well. It also provides information about the radiative transition energies in all the layers. In order to obtain either the trap activation energies and the detrapping rates of photogenerated carriers in the GaInNAs the IPV results are analyzed in terms of a theoretical model based on random doping fluctuations in nominally undoped multilayer structures. The PL results are analyzed in terms of the band anticrossing model to obtain the electron effective mass from the coupling parameter C NM .
Optical properties of GaInNAs/GaAs quantum wells
Solid-State Electronics, 2003
We report the results of our studies of optical and electro-optic properties of GaInNAs/GaAs single quantum wells grown by chemical beam epitaxy. The quantum wells have been characterised by scanning transmission electron microscopy and energy dispersive X-ray analysis. Photoluminescence measurements from sequentially grown GaInAs and GaInNAs quantum wells were carried out between 4 K and room temperature. A significant difference in the temperature dependence of GaInNAs band gap compared to nitrogen-free GaInAs is observed. Photoluminescence results are used to determine the interband transition energies. The results are compared with the theoretical values obtained using the band-anticrossing model. When the device is illuminated with monochromatic light, a finite photovoltage develops in the plane of the quantum wells due to Fermi level fluctuations.
Photoluminescence studies in modulation doped GaInNAs/GaAs multiple quantum wells
physica status solidi (c), 2007
We report for the first time the temperature dependent PL spectra from GaInNAs/GaAs triple quantum wells, modulation doped with a 2-D carrier density of ~3x10 11 cm -2 per well. The measurements were carried out at temperatures between 10 and 300K. The results are analyzed using a Gaussian fitting technique which indicates variable nitrogen composition and/or well-width fluctuations in the wells. One of the most striking features of the results is the lack of the S-Shape temperature dependence of the PL peak energy that is commonly observed in undoped dilute nitride quantum wells and is attributed to exciton detrapping, which screens the true temperature dependence of the energy gap. Our results compare well with the predictions of the Varshni equation. The temperature dependence of the PL intensity is used to obtain the thermally activated behaviour of the non-radiative recombination processes that appear to dominate at higher temperatures.
Japanese Journal of Applied Physics, 2013
Dynamics of excitons in GaInNAs/GaAs quantum wells (QWs) is studied theoretically within a model of hopping excitons. In this model the temporal evolution of photoluminescence (PL) is described by the system of rate equations which takes into account hopping of excitons between randomly generated localizing states. In this work we study the influence of temperature on such characteristic features of PL as the decay and rise time of PL signal as well as their spectral dependences. It is clearly shown that our model reproduces experimental data very well.
Photoluminescence from InAsN quantum dots embedded in GaInNAs/GaAs quantum wells
Journal of Applied Physics, 2007
Photoluminescence ͑PL͒ from InAsN quantum dots embedded in a GaInNAs/GaAs quantum well ͑QW͒ has been investigated at low excitation conditions in the temperature range of 15-305 K. A very efficient emission at 1.3 m with a small spectral broadening ͑30 meV͒ has been observed at room temperature for this system. The emission intensity decreases by only two decades in the whole investigated temperature range. Carrier escape into the states of the surrounding QW has been recognized as the main PL thermal quenching mechanism and the possible quenching via defect states has appeared to be negligible in this regime of excitation.
Optical characteristics of 1.55 μm GaInNAs multiple quantum wells
2004
We report the optical characterization of high-quality 1.55μm GaxIn1−xNyAs1−y multiquantum wells (MQWs), grown on GaAs with Ga(In)N0.01As spacer layers. The transitions between the quantized QW states of the electrons and holes have been identified using photoluminescence excitation spectroscopy. Their energies are consistent with theoretical fitting based on the band anticrossing model. It is also confirmed by detailed spectroscopic measurements that the addition of even a small amount of In to GaN0.01As barriers remarkably improves the optical characteristics of the QWs. The results imply that although strain-compensated GaInNAs MQWs provide a feasible approach to realizing 1.55μm optical emission, the relative lattice mismatch between the wells and barriers is critical to the optical quality of the related QWs.
Structural and optical properties of GaInNAs/GaAs quantum structures
Journal of Physics: Condensed Matter, 2004
Structural and optical properties of GaInNAs/GaAs quantum structures grown by metalorganic vapour phase epitaxy (MOVPE) are studied. The growth of arsenide-nitrides by MOVPE is reviewed and compared to the other major growth technique, molecular beam epitaxy. Post-growth thermal annealing and laser irradiation are employed and found to affect GaInNAs quantum wells differently: with laser treatment no undesired blue-shift of the photoluminescence peak is observed. The critical thickness for misfit dislocation formation of GaAsN on GaAs is found to be about twice as large as the theoretical prediction. GaAsN epilayers are also found to contain Ga vacancies in defect complexes. The current status of experimental research on GaInNAs quantum dot structures is reviewed. Self-organized and straininduced GaInNAs quantum dots are grown and their formation and optical properties are studied. The emission wavelength of InGaAs quantum dots is extended by using InGaAs and GaInNAs barrier layers.
Optical and Quantum Electronics, 2007
The effect of In-segregation on optical properties in 7.5-nm GaInNAs/GaAs single quantum well (QW) is studied theoretically. The nominal (In, N) contents in the QW are chosen to be (0.35, 0.015) and (0.39, 0.03) for the emission wavelengths around 1.3 and 1.55 μm, respectively. Muraki's model is used to model the composition profiles in the QWs. In-plane strain, confinement potential, and subband energy levels of the QW are calculated using multi-band effective mass theory. We show a space-indirect transition between light holes localized in indium deficient region and electrons localized in indium rich region of the quantum well. Our results show that the optical transition energies are approximately constant for the segregation efficiencies smaller than 0.7 in both QWs.