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Développement de briques technologiques pour la réalisation de transistors MOS de puissance en Nitrure de Gallium

Elias Al Alam 1
1 LAAS-ISGE - Équipe Intégration de Systèmes de Gestion de l'Énergie
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : Gallium Nitride (GaN) semiconductor is one of the most promising materials for new power devices generation thanks to its outstanding material properties for high voltage, temperature and frequency applications. The higher and higher efficiency demanded in future switch power applications requires the investment on normally-off transistors in GaN substrates. Hence, the main objective of this thesis was the development and optimization of a technological process with the purpose of fabricating a GaN power MOS transistor. Then, a first definition of the normally-off GaN power transistor design has been carried out after an extended evaluation of the state-of-the-art. The gate dielectric deposition technological step which gives the quality of the dielectric/GaN interface is the cornerstone of a high performance GaN power transistor. This important step includes the GaN surface preparation, the formation of an interface layer and the subsequent deposition of the dielectric. We have observed that an UV-oxidation step combined with plasma oxidation before the dielectric deposition highly improves the GaN surface quality and minimizes the concentration of contaminants in the dielectric/GaN interface. Besides, measurements performed in fabricated MOS structures to determine the interface trap density of the obtained dielectric/GaN have shown significant differences related to the epitaxial growth type (MBE or MOCVD), especially to the type (N or P) and doping concentration of the GaN substrate. Correlations between the physical-chemistry of the interface and the electrical properties of MOS structures are also investigated in this work. In addition, other necessary technological steps for the fabrication of a GaN MOSFET have been analysed, especially those concerning the N and P type ionic implantation and the reactive-ion etching. All the results presented in this work will allow, in the near future, the design of high quality normally-off power MOS transistors in GaN substrate. However, there are still have scientific and technological challenges to overcome before obtaining the high efficiency power switch demanded in future switch applications.
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Submitted on : Friday, September 16, 2011 - 8:53:37 AM
Last modification on : Thursday, June 10, 2021 - 3:04:21 AM
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  • HAL Id : tel-00624190, version 1


Elias Al Alam. Développement de briques technologiques pour la réalisation de transistors MOS de puissance en Nitrure de Gallium. Micro et nanotechnologies/Microélectronique. Université Paul Sabatier - Toulouse III, 2011. Français. ⟨tel-00624190⟩



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