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Relaxation de la contrainte dans les hétérostructures Al(Ga)InN/GaN pour applications électroniques : modélisation des propriétés physiques et rôle de l'indium dans la dégradation des couches épitaxiales

Abstract : For the fabrication of nitride-based power microwave transistors, the InAlN alloy is considered to be a better barrier than AlGaN thanks to the lattice match with GaN for an indium composition around 18%. Thus the two-dimensional electron gas (2DEG) is generated only by the spontaneous polarization at the AlInN/GaN heterointerface for a production of highest performance transistors. However, during its growth on GaN, its crystalline quality deteriorates with the thickness and V-defects are formed at the layer surface. To determine the sources of this behavior, we carried out a theoretical study by molecular dynamics and ab initio techniques to analyze the stability and the properties of alloys of nitride compounds, focusing particularly on InAlN. The analysis of the phase diagrams showed that this alloy has a wide zone of instability versus the indium composition and a different behavior with InGaN with amplified instability under high compressive strain. By determining the energetic stability of the nitrogen vacancy could be catalyst for forming clusters in this alloy. These InN clusters introduce deep donor levels inside the band gap. With regard to treading dislocations, our results show that they will also tend to capture indium atoms in their cores in order to minimize their energy. Thus, we have been able to provide a theoretical basis that show that the nitrogen vacancy participates in the spontaneous degradation of the AlInN layers and that the threading dislocations participate by attracting the indium atoms and thus reinforcing the separation of phase in their vicinity.
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https://tel.archives-ouvertes.fr/tel-01943769
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Submitted on : Tuesday, December 4, 2018 - 10:35:44 AM
Last modification on : Thursday, January 14, 2021 - 9:45:49 AM

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Ranim Mohamad. Relaxation de la contrainte dans les hétérostructures Al(Ga)InN/GaN pour applications électroniques : modélisation des propriétés physiques et rôle de l'indium dans la dégradation des couches épitaxiales. Physique [physics]. Normandie Université, 2018. Français. ⟨NNT : 2018NORMC229⟩. ⟨tel-01943769⟩

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