Temperature-dependent photoluminescence spectra of GaAsSb/AlGaAs and GaAsSbN/GaAs single quantum wells under different excitation intensities

Abstract

The mechanism for low-temperature photoluminescence (PL) emissions in GaAsSb/AlGaAs and GaAsSbN/GaAs strained-layer single quantum wells (SQWs), grown by molecular-beam epitaxy, is studied in detail, using PL spectroscopy as a function of temperature and excitation intensity. In all samples, the PL peak energy as well as the full width at half maximum (FWHM), as a function of temperature, present anomalous behaviors, i.e., the PL peak energy shows a successive red/blue/redshift (S-shaped behavior) and the FWHM shows a successive blue/red/blueshift ("inverted S-shaped curve") with increasing temperature. At sufficiently low excitation intensity and in a narrow temperature interval (50-80 K), the nitrogen-containing samples present two clear competitive PL peaks. The low-energy PL mechanism (8-80 K) is dominated by localized PL transitions, while the high-energy PL mechanism is dominated by the ground state (e1-hh1) PL transition. Additionally, these PL peaks show different temperature dependence with the low-energy PL peak, showing a stronger redshift than the high-energy PL peak. A competition process between localized and delocalized excitons is used to discuss these PL properties.

Correlation between optical properties surface morphology of porous silicon electrodeposited by Fe 3+ ion

“…This S-shape behavior has already been observed by several authors [30][31][32][33] and has been attributed to localized exciton (LE) by potential fluctuations induced by random distribution of impurities, defects and alloy disorder in samples [34]. The S-shape disappears in the case of PSF22 sample where E PL (T) presents a temperature variation according to BoseEinstein model [35] (See Fig.…”

Substrate orientation effect on potential fluctuations in multiquantum wells of GaAs∕AlGaAs

“…This phenomenon was also observed in GaAs/ AlGaAs and GaAsSb/ AlGaAs simple QWs, 17,18 and it was interpreted as competition between the blueshift ͑due to potential fluctuations͒ and the redshift ͑due to band-gap renormalization͒. The temperature T X at which the crossing takes place was interpreted as a point where the competition between the mechanism of band-gap renormalization and potential fluctuation is at its maximum.…”

“…Below T X , the potential fluctuations dominate the excitonic transitions, and for temperature values superior than T X , the effect of band-gap energy renormalization starts to predominate. 18,19 Taking this into account, it can be observed that on ͑311͒ surfaces, the values of T X are higher than those on ͑100͒, showing that the potential fluctuations are higher in those surfaces.…”

“…[12][13][14][15][16][17] It has been argued that under intermediated-excitation intensities, there is competition between the potential fluctuations and the band-gap renormalization effects, which is related to the radiative-recombination energy of the carriers. 18 preted as a value at which the mechanisms of band-gap renormalization and potential fluctuations cancel each other.…”

“…[17][18][19][20] As far as we know, studies about the influence of substrate orientation on potential fluctuations in QWs are lacking. This article aims to analyze the influence of the substrate orientation on the potential fluctuations of GaAs/ Al x Ga 1−x As MQWs grown on ͓100͔ ͓311͔A, and ͓311͔B oriented GaAs substrates.…”