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Nanostructures quantiques propriétés optiques
(36) Production(s) de l'année 2018

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Photoluminescence of GaN and AlxGa1-xN (x≤ 0.2) doped with Mg and grown by molecular beam epitaxy

Auteur(s): Leroux Mathieu, Brault Julien, Matta S., Al khalfioui Mohamed, Damilano Benjamin, Contreras S., Juillaguet S., Konczewicz L., Gil B., Brochen S.

(Affiches/Poster) JNMO (Cap Esterel-Aguay, FR), 2018-06-13

(Al,Ga)N quantum dots for deep UV LEDs

Auteur(s): Brault Julien, Matta S., Al khalfioui Mohamed, Korytov M, Ngo T. H., Vuong P., Leroux Mathieu, Damilano Benjamin, Chenot S., Vennegues P, Duboz J. y., Massies Jean, Chaix C., Peyre H., Juillaguet S., Contreras S., Gil B.

Conference: International Workshop on Nitride Semiconductor (Kanazawa, JP, 2018-11-11)

Effect of Temperature on Electrical Transport Properties of MBE grown Mg-doped GaN and AlGaN

Auteur(s): Contreras S., Konczewicz L., Juillaguet S., Peyre H., Al Khalfioui Mohamed, Matta S., Leroux Mathieu, Damilano Benjamin, Gil B., Brault Julien

(Affiches/Poster) International Workshop on Nitride Semiconductor (Kanazawa, JP), 2018-11-11

Photoluminescence study of Mg-doped GaN and AlxGa1-xN (x<0.4) grown by molecular epitaxy

Auteur(s): Brault Julien, Leroux Mathieu, Matta S., Al Khalfioui Mohamed, Damilano Benjamin, Peyre H., Contreras S., Juillaguet S., Gil B. (Corresp.)

(Affiches/Poster) International Workshop on Nitride Semiconductor (Kanazawa, JP), 2018-11-11

Les technologies quantiques

Auteur(s): Robert-Philip I.

Conférence invité: Quantum Computing day (Montpellier, FR, 2018-03-27)

Quantum sensing with diamond

Auteur(s): Robert-Philip I. (Corresp.) , Tanos R., Akhtar M. W., Jacques V., Gergely C., Baffou Guillaume, Monneret Serge, Munsch Mathieu, Favaro Felipe, Maletinsky P.

Conférence invité: International Symposium on Quantum Technologies (Shanghai, CN, 2018-10-30)

Phase transition of indirect excitons in GaN quantum wells.

Auteur(s): Guillet T. (Corresp.) , Chiaruttini F., Brimont C., Bretagnon T., Doyennette L., Lefebvre P., Valvin P., Damilano Benjamin, Chenot Sebastien, Cordier Yvon, Vladimirova M.

Conference: International Workshop on Nitride semiconductors - IWN2018. (Kanazawa, JP, 2018-11-11)

Ref HAL: hal-01910225_v1
Exporter : BibTex | endNote
Résumé:

Excitons in wide nitride Quantum Wells (QWs) are naturally indirect due to the strong internal electric field: within such excitons the electron and the hole are spatially separated, resulting in strong dipole moments and long radiative lifetimes. These properties offer the possibility to explore the collective exitonic phases with complex phase diagrams predicted theoretically in the temperature-density-dipole moment parameter space. Here we study 8 nm-wide GaN/(AlGa)N QWs presenting 1MV/cm built-in electric field in the growth direction, microsecond-long radiative lifetimes, 8 meV exciton emission linewidth and 100 µm transport lengths at cryogenic temperatures. To address the quasi-equilibrium properties of the strongly dipolar excitons (i.e. whose electric dipoles are twice as long as their Bohr radii d = 2aB), we confine them in the QW’s plane using electrostatic traps with a semi-transparent Schottly electrode. These traps consist in semitransparent electrodes deposited on the sample’s surface. We make micro-photoluminescence (µPL) measurements (less than 1µm- resolution) upon point-like optical excitation. We thus obtain the spectrally resolved information on the emission of the excitons as a function of power and density. Our experiments demonstrate an efficient trapping of excitons in the plane of the QW, with a trapping potential of an order of 50 meV. We demonstrate that it is possible to uniformly fill areas up to hundreds of microns in length with excitons and/or electron hole pairs in the QW’s plane. At T=4K, the emission from these areas exhibits a peculiar behavior. At low densities, such that there is no measurable screening of the built-in electric field, the emission from the trap is weak and spatially homogeneous. However, for weak built-in electric field screenings (as low as 10 meV, ~1011 cm-2 pair density), the PL brightens up and becomes spatially inhomogeneous – droplet like. We tentatively interpret this fragmentation as the coexistence of the gas and liquid phases of the excitons. As expected, the fragmented character of the emission disappears when either power and/or temperature is further increased, due to either exciton heating (gas phase), ionization or dissociation (Mott transition). Our results suggest that excitons in GaN QWs are promising candidates for the study of collective phenomena in cold dipolar bosonic systems. The advantages of the nitrides over arsenides include both higher critical temperatures for the onset of collective phenomena, and the ability to increase the dipolarity of systems based on their small exciton Bohr radius.

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Nanostructures quantiques propriétés optiques
(36) Production(s) de l'année 2018

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Recherche approfondie

Nanostructures quantiques propriétés optiques(36) Production(s) de l'année 2018

Nanostructures quantiques propriétés optiques
(36) Production(s) de l'année 2018