Réalisation et étude de nanostructures de (Ga)InAs épitaxiées sur un substrat d'InP

Abstract : We have studied the structural and optical properties of self-assembled (Ga)InAs quantum dots grown by gas source molecular beam epitaxy on (001) and (113)B InP substrates. The elastic relaxation process (i.e. the 2D to 3D growth mode transition) of the strained (Ga)InAs layer on the (001) orientation, evolves continuously from the twodimensional growth to the formation of 2–8 monolayer high platelets, and then to quantum dots if the growth is interrupted for a sufficient time. In the platelets, the in-plane diffusion of the electrons is limited and the non-radiative recombination at room temperature is reduced.The high optical efficiency of the platelets could make them suitable candidates for the active zone of a laser, but the control of their size and emission wavelength is very difficult. The InAs/InP quantum dots are twice as big as the InAs/GaAs ones and the dot density is lower. Using a new characterization technique, we demonstrate that the photoluminescence linewidth is directly related to the distribution of the dot sizes. The dots also are good traps for carriers up to the room temperature and have been successfully used in the trapping zone of photorefractive devices. For (Ga)InAs layers with different gallium concentrations, we have observed an elongation of the dots along the [1 1 0] crystallographic direction, which is enhanced by a lower lattice mismatch and a higher nominal thickness of the layers. High index (113)B InP substrates favor the elastic relaxation of the strain and gives rise to a higher dot density. The resulting quantum dots are smaller with a narrower size distribution than on the (100) InP substrate and are defined by low index facets. The dot density increases linearly with the amount of InAs deposited and at high density the dots tend to form a square array. Finally, we have exposed the dots to a phosphorous overpressure and reduced the dot size through arsenic/phosphorous exchange. We have achieved a reproducible luminescence emission wavelength at 1.55 μm, which is of great interest for optical telecommunications.
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Sylvain Fréchengues. Réalisation et étude de nanostructures de (Ga)InAs épitaxiées sur un substrat d'InP. Matière Condensée [cond-mat]. INSA RENNES, 1998. Français. ⟨tel-02288228⟩

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