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Last name: MORANCHO
First name: Frédéric
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Different technologies have been developed for the realization of AlGaN/GaN HEMTs exhibiting the normally-off functionality, such the gate recess or the introduction of a P-GaN layer for lifting-up the conduction band level under the gate. Despite their respective advantages, the major drawbacks are the degradation of the carriers mobilities in...
Les travaux portent sur la réalisation technologique d'un HEMT AlGaN/GaN normally-off avec une grille à barrière P-GaN. Des résultats de simulation ont montré que la tension de seuil de cette structure peut atteindre une valeur supérieure à 2 V et qu'elle est liée à la profondeur de gravure de la couche d'AlGaN. Nous avons développé une recette...
A new normally-off AlGaN/GaN HEMT structure is proposed. The regrowth of a P-GaN layer on the AlGaN/GaN heterostructure after the gate recess allows the achievement of the enhancement mode. A shift in the threshold voltage to positive values has been proved through simulation results. A precise control of the etch depth for the gate recess is detailed.
The technology of GaN HEMT structures is the subject of major developments for large-gap power components. However, it is necessary to develop innovative technological solutions to obtain high-performance normally-off devices. We present a new normally-off structure based on a nanostructured P-GaN multi-well gate. The design of this structure,...
In this work, C-V characteristics of MOS capacitors fabricated by depositing SiO2 by plasma-enhanced chemical-vapor-deposition at low temperature (300 degrees C) on an N-type GaN epitaxial layer have been performed to analyze the quality and reliability of the resultant MOS device. Additional information has been extracted by comparing the...
This paper proposes a new technique to engineer the Fin channel in vertical GaN FinFET toward a straight and smooth channel sidewall. Consequently, the GaN wet etching in the TMAH solution is detailed; we found that the m-GaN plane has lower surface roughness than crystallographic planes with other orientations, including the a-GaN plane. The...
Un nouveau concept d'interrupteur de puissance HEMT en GaN présentant la fonctionnalité « normally-off » est expérimentalement validé. L'introduction d'une couche P-GaN suffisamment dopée (autour de 2 x 10 18 cm-3) au sein de la couche buffer GaN NID, en-dessous de l'électrode de grille et sous l'interface AlGaN / GaN, permet d'obtenir une...
MOS SiO2/GaN structures were fabricated with different surface preparation and different PECVD processes for the dielectric thin film deposition (ECR-PECVD and ICP-PECVD in continuous and pulsed modes). On the basis of C-V curves, the surface preparation steps, involving chemical etching with BOE, UV-Ozone oxidation and oxygen plasma oxidation,...
MOS SiO2/GaN structures were fabricated with different surface preparation and different PECVD processes for the dielectric thin film deposition (ECR-PECVD and ICP-PECVD in continuous and pulsed modes). On the basis of C-V curves, the surface preparation steps, involving chemical etching with BOE, UV-Ozone oxidation and oxygen plasma oxidation,...
In this work, the physical and the electrical properties of vertical GaN Schottky diodes were investigated. Cathodo-luminescence (CL), micro-Raman spectroscopy, SIMS, and current-voltage (I-V) measurements were performed to better understand the effects of physical parameters, for example structural defects and doping level inhomogeneity, on...
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N-doped homo-epitaxial GaN samples grown on freestanding GaN substrates have been investigated by micro-Raman spectroscopy. Quantitative analysis of the Eh2 and the A1(LO) modes' behavior has been performed while intentionally increasing the carrier density using silicon doping. We noticed that as the carrier concentration increases up to 1.8 ×...
In this work, measurements from cathodo-luminescence (CL), micro-Raman spectroscopy and currentvoltage I(V) have been coupled to assess the effects of physical parameters such as threading dislocations and effective doping level homogeneity on the electrical performances of vertical GaN Schottky diodes.