VEZIAN , Stephane

This work deals with the gallium nitride (GaN) (0001) surface with gallium polarity. Indeed this particular orientation is used for the recent technological applications of this wide band-gap semiconductor. The experimental study of this surface is mainly based on the use of two local probe microscopies : atomic force microscopy (AFM) and...

Selective area thermal etching (SATE) of gallium nitride is a simple subtractive process for creating novel device architectures and improving the structural and optical quality of III-nitridebased devices. In contrast to plasma etching, it allows, for example, the creation of enclosed features with extremely high aspect ratios without...

We investigate the optical properties of porous GaN films of different porosities, focusing on the behaviors of the excitonic features in time-integrated and time-resolved photoluminescence. A substantial enhancement of both excitonic emission intensity and recombination rate, along with insignificant intensity weakening under temperature rise,...

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Relying on the local orientation of nanostructures, Pancharatnam-Berry metasurfaces are currently enabling a new generation of polarization-sensitive optical devices. A systematical mesoscopic description of topological metasurfaces is developed, providing a deeper understanding of the physical mechanisms leading to the polarization-dependent...

InGaN/GaN single quantum wells were grown by molecular beam epitaxy on the silicon substrate onto thin AlN and GaN buffer layers. The InGaN/GaN structure is porosified using a combination of Si x N y nanomasking and sublimation and compared with a non-porous reference. The photoluminescence efficiency at room temperature of the porosified...

We report on the fabrication of an enhancement mode p-GaN/AlN/GaN high electron mobility transistor with selective area sublimation under vacuum of the p-GaN cap layer. The GaN evaporation selectivity is demonstrated on the thin 2 nm AlN barrier layer. Furthermore, the regrowth of AlGaN is a major key to increase the maximum drain current in...

Nano-engineering III-Nitride semiconductors offers a route to further control the material and optoelectronic properties, enabling novel functionalities and applications. Although various lithography techniques are employed to nano-engineer these materials, the scalability and cost of the fabrication process can be an obstacle for...