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Your search keyword '"Couto, O. D. D."' showing total 22 results
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22 results on '"Couto, O. D. D."'

1. Revealing the impact of strain in the optical properties of bubbles in monolayer MoSe2

Author

Covre, F. S., primary, Faria, P. E., additional, Gordo, V. O., additional, de Brito, C. Serati, additional, Zhumagulov, Y. V., additional, Teodoro, M. D., additional, Couto, O. D. D., additional, Misoguti, L., additional, Pratavieira, S., additional, Andrade, M. B., additional, Christianen, P. C. M., additional, Fabian, J., additional, Withers, F., additional, and Galvão Gobato, Y., additional

Published
2022
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19. Strain redistribution at the phase transition of MnAs/GaAs(001) films.

Author

Adriano, C., Giles, C., Couto, O. D. D., Brasil, M. J. S. P., Iikawa, F., and Däweritz, L.

Subjects
DIFFRACTION patterns, OPTICAL diffraction, JOINT dislocations, X-ray optics, WOUNDS & injuries
Abstract

We investigated the thermal evolution of the lattice parameters of a MnAs film epitaxially grown on GaAs(001) around its magnetostructural first-order phase transition using x-ray diffraction. Despite the substrate constraint, large variation of one of the in-plane lattice parameters is preserved, typical of bulk MnAs phase transition, during a large temperature range where two phases coexist. We demonstrated that the condition of the constant film length along this direction, in accord to the substrate length, is always fulfilled during the process. The effect is attributed to the gliding of misfit dislocations present on the film. [ABSTRACT FROM AUTHOR]

Published
2006
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20. Effect of MnAs/GaAs(001) film accommodations on the phase-transition temperature.

Author

Iikawa, F., Brasil, M. J. S. P., Couto, O. D. D., Adriano, C., Giles, C., and Däweritz, L.

Subjects
PHASE transitions, MOLECULAR beam epitaxy, CRYSTAL growth, TRANSITION temperature, GRAZING incidence, X-ray diffraction
Abstract

The phase-transition temperature of MnAs epitaxial films grown by molecular-beam epitaxy on GaAs(001) with different crystalline accommodations was studied by specular and grazing incidence x-ray diffraction. The transition temperature of MnAs films with tilted hexagonal c-axis orientations with respect to the GaAs substrate is higher than the most investigated nontilted films and reaches a value above room temperature, which is more suitable for device applications. [ABSTRACT FROM AUTHOR]

Published
2004
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21. Acoustically-driven Single Photon Sources on (311)A GaAs.

Author

Lazic, S., Couto, O. D. D., Iikawa, F., Stotz, J. A. H., Hey, R., and Santos, P. V.

Subjects
*GALLIUM arsenide semiconductors, *PHOTONS, *ACOUSTIC surface waves, *QUANTUM wells, *NANOWIRES, *PHOTOLITHOGRAPHY, *ELECTRONIC structure, *FORCE & energy
Abstract

We employ surface acoustic waves to control the transfer of photo-generated carriers between interconnected quantum wells and wires grown on pre-patterned (311)A GaAs substrates. The wires are embedded at photo-lithographically defined positions within (Al,Ga)As/GaAs quantum well. Optical studies on these structures have shown sharp PL lines and antibunched photons with tunable emission energy, revealing the presence of several recombination centers within the wire. The spatial separation of these recombination centers emitting single photons is determined from time-resolved measurements. [ABSTRACT FROM AUTHOR]

Published
2011
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22. Revealing the nature of low-temperature photoluminescence peaks by laser treatment in van der Waals epitaxially grown WS 2 monolayers.

Author

Orsi Gordo V, Balanta MAG, Galvão Gobato Y, Covre FS, Galeti HVA, Iikawa F, Couto ODD, Qu F, Henini M, Hewak DW, and Huang CC

Abstract

Monolayers of transition metal dichalcogenides (TMD) are promising materials for optoelectronics devices. However, one of the challenges is to fabricate large-scale growth of high quality TMD monolayers with the desired properties in order to expand their use in potential applications. Here, we demonstrate large-scale tungsten disulfide (WS 2 ) monolayers grown by van der Waals Epitaxy (VdWE). We show that, in addition to the large structural uniformity and homogeneity of these samples, their optical properties are very sensitive to laser irradiation. We observe a time instability in the photoluminescence (PL) emission at low temperatures in the scale of seconds to minutes. Interestingly, this change of the PL spectra with time, which is due to laser induced carrier doping, is employed to successfully distinguish the emission of two negatively charged bright excitons. Furthermore, we also detect blinking sharp bound exciton emissions which are usually attractive for single photon sources. Our findings contribute to a deeper understanding of this complex carrier dynamics induced by laser irradiation which is very important for future optoelectronic devices based on large scale TMD monolayers.

Published
2018
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