VENNEGUES , P.

The microstructure of (11‐20) GaN films grown on (1‐102) sapphire substrates is studied by transmission electron microscopy. The predominant defects emerging at the surface of a 1‐2 μm thick layers are basal stacking faults of I1 type (1/6<20‐23> displacement vector). These defects are either terminated in the films by partial dislocations with...

Thanks to close crystalline structures and low lattice mismatches, nonpolar (11 (2) over bar0) 6H-SiC is expected to be a well- adapted substrate for the growth of nonpolar (11 (2) over bar0) III-nitride films. We demonstrate that the local reproduction of the basal planes stacking induces the presence of numerous planar defects (1.3 x 10(6)...

Thanks to close crystalline structures and low lattice mismatches, nonpolar (11 (2) over bar0) 6H-SiC is expected to be a well- adapted substrate for the growth of nonpolar (11 (2) over bar0) III-nitride films. We demonstrate that the local reproduction of the basal planes stacking induces the presence of numerous planar defects (1.3 x 10(6)...

Strain relaxation mechanisms in metal-organic vapour phase epitaxy grown (Al,Ga)N/GaN heterostructures are presented. Relaxation first occurs through a 2D–3D transition. For pure AlN, misfit a-type dislocations are introduced at the coalescence front of growth islands. For (Al,Ga)N (Al concentration≤70%), the second relaxation step is cracking....

The relaxation mechanisms in metal-organic vapor phase epitaxy grown (Al,Ga)N∕GaN heterostructures are studied. The first stage of the relaxation process is a two-dimensional–three-dimensional growth transition with the formation of mesalike islands separated by V-shaped trenches. The tensile stress relief is obtained by an elastic relaxation...

New conditions for one‐step ELO were implemented to grow coalesced (11equation image0) non‐polar and (11equation image2) semi‐polar GaN layers starting, respectively, from R ‐ and M ‐plane sapphire. A great part of the stacking faults (SFs) and dislocations are filtrated resulting in GaN material with better structural and optical properties....

XE examine the impact of the heterostructure design at the scale of the structural and optical properties for yellow light emission

We report on the synthesis of new nitride-based compound by using annealing of AlN heteroepitaxial layers under a Si-atmosphere at temperatures between 1350°C and 1550°C. The structure and stoichiometry of this compound are investigated by high-resolution scanning transmission electron microscopy (HRSTEM), energy dispersive X-Ray (EDX)...

International audience

International audience

Les lasers et amplificateurs à fibres optiques à base de silice dopée d'ions de terres rares (TR) sont développés pour de nombreuses applications. Toutefois, la silice impose des limites à l'amélioration des performances spectroscopiques de nouveaux dispositifs. Pour s'en affranchir, il est proposé d'insérer les ions de TR dans des...

Rare-earth-doped (RE) silica-based optical fiber lasers and amplifiers are developed for numerous applications. However, silica glass has certain characteristics (high phonon energy, low RE solubility, …) which may be detrimental for the luminescence properties of RE. To overcome this issue, the incorporation of RE in nanoparticles is...

Les lasers et amplificateurs à fibres optiques à base de silice dopée d'ions de terres rares (TR) sont développés pour de nombreuses applications. Toutefois, la silice impose des limites à l'amélioration des performances spectroscopiques de nouveaux dispositifs. Pour s'en affranchir, il est proposé d'insérer les ions de TR dans des...

International audience

L'amélioration des propriétés de luminescence du thulium dans la silice par des nanoparticules ainsi que la limitation des pertes optiques sont discutées. INTRODUCTION Le verre de silice est le matériau le plus communément utilisé pour fabriquer des fibres optiques. Cependant, certaines des propriétés de ce verre (énergie de phonon élevée,...