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(321) Production(s) de GIL B.
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Thermal annealing of molecular beam epitaxy-grown InGaN/GaN single quantum well 
Auteur(s): Kaufmann Nils, Dussaigne Amélie, Martin Denis, Valvin P., Guillet T., Gil B., Ivaldi Francesco, Kret Slawomir, Grandjean N.
(Article) Publié:
Semiconductor Science And Technology, vol. 27 p.105023 (2012)
Texte intégral en Openaccess : 
Ref HAL: hal-00805853_v1
DOI: 10.1088/0268-1242/27/10/105023
WoS: 000309111800025
Exporter : BibTex | endNote
16 Citations
Résumé: The effect of thermal annealing on In0.25Ga0.75N/GaN quantum wells grown by molecular beam epitaxy at 550°C is investigated. A strong increase in the 300 K photoluminescence (PL) intensity is observed for samples annealed at 880°C, while degradation occurs for higher temperatures. The improvement of the optical properties is ascribed to higher internal quantum efficiency (IQE), as indicated by temperature-dependent and time-resolved PL experiments. The effect of carrier localization due to possible quantum dot formation via indium clustering is ruled out based on high-resolution transmission electron microscopy imaging. IQE improvement is thus attributed to a reduction of point defects upon annealing.
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Time-resolved photoluminescence of high-aluminum-content (Al,Ga)N quantum wells and epilayers emitting in the 215-255 nm range.
Auteur(s): Lefebvre P., Brimont C., Valvin P., Miyake H., Hiramatsu K., Gil B.
(Affiches/Poster)
International Workshop on Nitride semiconductors (IWN 2012). (Sapporo, JP), 2012-10-14
Ref HAL: hal-00797472_v1
Exporter : BibTex | endNote
Résumé: Time-resolved photoluminescence of high-aluminum-content (Al,Ga)N quantum wells and epilayers emitting in the 215-255 nm range.
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Advanced spectroscopy in ZnO-based heterostructures
Auteur(s): Gil B.
Conférence invité: International School on spin optronics (Saint Pétersbourg, RU, 2012-07-10)
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Optical spectroscopy of III-nitrides
Auteur(s): Gil B.
Conférence invité: Summer School on III nitride optoelectronics (Sheffield, GB, 2012-07-02)
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How time resolved spectroscopy helped tailoring designs of nitride-based LEDs
Auteur(s): Gil B.
Conférence invité: International scientific seminar on actual problems of physics of semiconductors (Saint Pétersbourg, RU, 2012-10-25)
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Nonlinear spectral hole-burning of the intraband transition at 1.55 μm in GaN/AlN quantum dots
Auteur(s): Nguyen Dac-Trung, Tchernycheva M., Julien F. H., Monroy E., Gil B., Cassabois G.
Conference: International Workshop on Nitride semiconductors (IWN2012) (Sapporo, JP, 2012-10-15)
Ref HAL: hal-00744476_v1
Exporter : BibTex | endNote
Résumé: GaN/AlN quantum dots are semiconductor nanostructures where the huge conduction band offset of 1.75 eV leads to intraband transitions at exceptionnaly short wavelengths compared to III-As semiconductor materials. For specific quantum dot dimensions, it was shown that the absorption spectrum covers the optical communication spectral range. The ultrafast relaxation dynamics observed for these materials motivates the development of opto-electronic devices, and especially ultrafast switches. However, a detailed insight into the microscopic processes governing the relaxation dynamics is still missing although of fundamental importance for the understanding and the optimization of the devices operation. In particular, there is no study of the homogeneous broadening which drives the saturation properties of GaN/AlN quantum dots-devices. In this paper, we present homogeneous linewidth measurements by means of the nonlinear optical technique of spectral hole-burning. Spectrally-resolved pump-probe experiments with cw-lasers allow us to characterize the coherence relaxation dynamics down to 5K by resolving the homogeneous linewidth in an ensemble of GaN/AlN quantum dots. The differential transmission measured at 5K for a TM-polarized pump shows a pronounced bleaching with an amplitude of 2x10-4 on a background signal of 5x10-5. According to the selection rules of the s-pz intraband transition in GaN/AlN QDs, we attribute the photoinduced increase of the probe transmission to the partial saturation of the quantum dots by the pump laser, and we deduce a homogeneous linewidth of 15 meV at 5K. We find that the differential transmission signal scales like the square-root of the incident pump power, thus revealing the importance of electron-electron scattering in the population relaxation dynamics. As a matter of fact, we find that the population relaxation from the pz excited state is predominantly governed by Auger-type processes whereas optical phonon emission only plays a minor role, even if it may contribute to secondary processes during the carrier cascade to the fundamental s state via intermediate confined states.
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