GaAsSbN/GaAs strained-layer single quantum wells grown on a GaAs substrate by molecular-beam epitaxy with different N concentrations were studied using the photoluminescence ͑PL͒ technique in the temperature range from 9 to 296 K. A strong redshift in optical transition energies induced by a small increase in N concentration has been observed in the PL spectra. This effect can be explained by the interaction between a narrow resonant band formed by the N-localized states and the conduction band of the host semiconductor. Excitonic transitions in the quantum wells show a successive red/blue/redshift with increasing temperature in the 2-100 K range. The activation energies of nonradiative channels responsible for a strong thermal quenching are deduced from an Arrhenius plot of the integrated PL intensity.

Articles you may be interested inGaAsSb/GaAsN short-period superlattices as a capping layer for improved InAs quantum dot-based optoelectronics Appl. Phys. Lett. 105, 043105 (2014); 10.1063/1.4891557Molecular-beam epitaxy of phosphor-free 1.3 μ m InAlGaAs multiple-quantum-well lasers on InP (100) Midinfrared InGaAsSb quantum well lasers with digitally grown tensile-strained AlGaAsSb barriers Growth of high-quality GaAs/AlAs Bragg mirrors on patterned InP-based quantum well mesa structuresWe identify quasi-donor-acceptor pair transitions in the photoluminescence spectra of GaAsSb and AlGaAsSb layers, lattice matched to InP, and grown by molecular-beam epitaxy. These alloys show compositional inhomogeneity due to phase separation resulting from miscibility gaps. The presence of Al in the quaternary alloy increases the fluctuation of the electrostatic potential in the epitaxial layer, increasing the variation of recombination energy as a function of intensity excitation in the range of low temperatures.

A study was conducted on potential fluctuations using the photoluminescence (PL) technique with temperature and excitation intensity variations, in a sample containing InGaAs∕InGaAlAs coupled double quantum wells, with spikes of InGaAlAs of different thicknesses, and a single quantum well as the control. With the inclusion of a spike at the center of the well, an increase in the magnitude of the potential fluctuation occurs, in relation to the control well, due to an increase in the contribution from both the interface roughness and the compositional disorders to the potential fluctuations. The enhancement of the effects of the potential fluctuations, such as the PL linewidth and the blueshift of the PL peak energy with the temperature, as the spike thickness increases, was attributed to the increase in the contribution from the alloy composition fluctuation to the potential fluctuation, caused by an increase in the interaction of the wave function with the central and lateral barriers. This study also discusses the strong influence of the excitation intensity on the variation of the emission energy with temperature.

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We present the results of our studies on the emission properties of In 0.53 Ga 0.47 As/ In 0.525 Ga 0.235 Al 0.25 As single and coupled double quantum wells ͑CDQWs͒ with different degrees of potential fluctuation. We have verified that the curve of the temperature ͑T͒ dependence of the emission peak energy ͑E PL ͒ is significantly influenced by the potential fluctuations ͑which are magnified by the presence of the internal barrier in the CDQW͒ as well as by the excitation density used in the photoluminescence ͑PL͒ measurements. As the excitation power increases, two effects occur simultaneously: the filling of the band-tail states related to potential fluctuations and the band-gap renormalization ͑BGR͒ caused by the increase in the density of photogenerated carriers. As the optical density increases, the E PL can shift to either higher ͑blueshift͒ or lower ͑redshift͒ energies, depending on the temperature at which the measurements are carried out. The temperature at which the displacement changes from a blueshift to a redshift is governed by the magnitude of the potential fluctuations and by the variation of BGR with excitation density.