Mechanism for low-temperature photoluminescence in GaNAs/GaAs structures grown by molecular-beam epitaxy

Abstract

The mechanism for low-temperature photoluminescence (PL) emissions in GaNAs epilayers and GaAs/GaNxAs1−x quantum well (QW) structures grown by molecular-beam epitaxy is studied in detail, employing PL, PL excitation, and time-resolved PL spectroscopies. It is shown that even though quantum confinement causes a strong blueshift of the GaNAs PL emission, its major characteristic properties are identical in both QW structures and epilayers. Based on the analysis of the PL line shape, its dependence on the excitation power and measurement temperature, as well as transient data, the PL emission is concluded to be caused by a recombination of excitons trapped by potential fluctuations in GaNAs.

Effect of temperature on the optical properties of GaAsSbN/GaAs single quantum wells grown by molecular-beam epitaxy

“…33,36,37 The degradation of PL efficiency at low N concentration in III-V semiconductor materials has been reported by several research groups. 12,42,43 Buyanova et al, for example, 43 observed similar nonradiative recombination channels, with activation energy of 50 meV, in the GaAsN/GaAs system. They suggested that these efficient competing nonradiative channels are located in the GaAsN layer, and that these channels are activated as soon as carriers are thermally detrapping from the localized states.…”

“…Similar results have been found in InGaNAs and GaAsN samples. 1,10,12 At low temperature, the PL spectra of both samples have an asymmetric behavior with an exponential tail at the lower-energy side, a characteristic of localized excitonic recombinations due to potential fluctuations. 16 -20 Several studies have shown that in QW heterostructures, random fluctuations of the alloy composition and roughness of the barrier-well interfaces are determinant factors of sample quality.…”

“…3,[9][10][11][12][13][14][15] Many works have demonstrated that the disorder in the InGaNAs alloy has a strong effect on the carrier motion, and that the radiative recombinations are generally dominated by localized excitons. [11][12][13][14][15] These works also suggest that the microscopic origin of the localized states is related either to the formation of In-N clusters, 11,13,15 or to the well width fluctuations and/or the local strain field induced by the presence of N. 11,14 Ungaro et al 3 have recently demonstrated that semiconductor alloys from the material-GaAsSbN-grown on a GaAs substrate can be used to prepare optical devices that emit light at room temperature in the 1.3-1.55 m wavelength range. 3,9 In particular, 100-Å-thick GaAs 0.825 Sb 0.15 N 0.025 /GaAs quantum wells ͑QWs͒ have demonstrated emission at 1.57 m. 9 In the present study, we investigated the temperature dependence of excitonic recombination in the GaAsSbN/GaAs QWs in the 9-296 K range.…”

Structural properties of GaAsN∕GaAs quantum wells studied at the atomic scale by cross-sectional scanning tunneling microscopy

“…Nevertheless, the optical emission of ͑In͒GaAsN / GaAs quantum wells ͑QWs͒ showed typically a strong degradation when the N content is increased. [1][2][3] This has been frequently attributed to different phenomena, such as N being incorporated in interstitial positions, 4,5 compositional fluctuations in the alloy, [6][7][8] or a rough top interface. 8 All these have motivated a strong effort in the last years on the structural characterization of ͑In͒GaAsN alloys, but only very few of these studies were performed using cross-sectional scanning tunneling microscopy ͑X-STM͒.…”

Epitaxially grown GaAsN random laser

“…1͑a͒. 10 The PL peak energy exhibits a strong shift to lower energies with increasing nitrogen content, which has been shown to correspond to the decrease in the band gap energy of this alloy due to the bowing effect. These characteristics have been well documented in the past.…”