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Incorporation du bismuth dans GaAs - Compréhension et maîtrise par couplage de mesures en temps réel de courbure et diffraction électronique

Clara Cornille 1, 2
1 LAAS-PHOTO - Équipe Photonique
LAAS - Laboratoire d'analyse et d'architecture des systèmes
2 LAAS-MPN - Équipe Matériaux et Procédés pour la Nanoélectronique
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : Research has been needed in large infrared devices, especially around 1.3µm in GaAs field. GaAsBi and derived alloys offer a large band structure engineering, make them a good candidate for 1eV solar cells, 1.3µm photocathodes or thermoelectric materials and spintronic. Though, the epitaxy of those III-V alloys is a challenge. In fact, they have a high lattice mismatch and bismuth incorporation is proved highly dependant of the growth conditions. First, we present the context of our study : we detailed their required properties for applications, and place ourseves amoung literature. We also describe the exploited techniques. Precise growth parameters can be selected by molecular beam epitaxy and they determine the structual characteristics of our material. We also have an original technique of real time coupling curvature measurement exploited with synchronized electronic diffraction. Bismuth incorporation study was made with those informations, obtained by varying growth conditions. Ex-situ techniques as X-Rays diffraction, Raman spectroscopy, Hall effect and Transmission Electronic Microscopy were also used to confort our original results. Then, we explained the different experimental studies we made on growth and caracterisation of those alloys. We pointed out a change in surface reconstruction during the growth, from the (1x3) reconstruction to the (2x1). We started to study the bismuth incorporation for the 2 surface reconstructions during growth, varying growth conditions : substrate temperature and elements fluxes. We exhibit a higher incorporation with the (1x3) reconstruction, and increasing for higher V/III flux ratio. Those conditions gave us growing GaAsBi layers with 2 different bismuth concentration. Then, we demonstrated the thermal activation of surface reconstruction transition, with the apparition of a surface stress, increasing with V/III ratios. Thirdly, we also validate our results on bismuth content by comparing their values with X ray diffraction, Rutherford Backscattering and transmission electron microscopy. Thank to his work, we obtained a comprehensive knowledge of bismuth incorporation in GaAs, and we developed it to consider further perspective for GaAsBi.
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Clara Cornille. Incorporation du bismuth dans GaAs - Compréhension et maîtrise par couplage de mesures en temps réel de courbure et diffraction électronique. Micro et nanotechnologies/Microélectronique. Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier), 2019. Français. ⟨tel-02907961⟩

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