Carrier Dynamics in Pure Wurtzite InP Nanowires Studied Using Optical-Pump Terahertz-Probe Spectroscopy

August 16-21, 2015International audienceno abstrac

Photocarrier Dynamics in Pure Wurtzite InP Nanowires probed by optical-pump terahertz-probe measurement

May 14-18, 2016International audienceno abstrac

Origins of nanoscale emission inhomogeneities of high content red emitting InGaN/InGaN quantum wells

International audienceThe origin of the nanoscale emission inhomogeneities of red emitting InGaN/InGaN quantum wells (QWs) grown directly on a GaN template and on an InGaN on sapphire (InGaNOS) substrate is investigated. InGaNOS is a partly relaxed InGaN pseudo-substrate fabricated by Soitec. As the latter approach provides an interesting optical internal quantum efficiency of 6.5% at 624 nm at 290 K, a deeper study, at the microstructure level, was conducted. The emission inhomogeneities on InGaNOS were highlighted by cathodoluminescence wavelength mappings where three areas were chosen: one emitting at a shorter wavelength, i.e., 588 nm, and two at a longer wavelength, i.e., 607 and 611 nm. Specimens from these zones were extracted by focused ion beam milling to perform cross-sectional characterization techniques. High-angle annular dark field scanning transmission electron microscopy images demonstrated that, while red emitting areas present homogeneous QWs, shorter wavelength areas exhibit non-uniform QWs, in terms of thickness and In composition. Complementary deformation mappings in the growth direction obtained by geometrical phase analysis show that longer emission wavelengths are originating from homogeneous QWs with an InN mole fraction evaluated at 39.0 ± 1.5%. This result demonstrates the possibility of achieving red emission with a coherent (In,Ga)N alloy when using an adapted substrate. A comparison of identical QWs grown on a GaN template is also given

Optical properties of wurtzite InP nanowires under hydrostatic pressure

December 13-16, 2015International audienceno abstrac

A 10.3 kbp Segment from nprB to argJ at the 102 Region of the Bacillus Subtilis Chromosome

The approximately 10 kbp region encompassing nprB and argJ at 102 on the Bacillus subtilis chromosome was sequenced, revealing 12 ORFs, four known genes (argJ, argC, ipi and nprB) and two genes, yitY and yitS, whose products respectively display significant homology with L-gulono-?-lactone oxidase of rat and dihydrofolate reductase of Staphylococcus aureus. The data also indicated that nprB mapped to a different position than previously published.</jats:p

Determination of the Properties of Composite Materials Thanks to Digital Image Correlation Measurements

AbstractDesigning composite structures for civil aircrafts necessitates a better understanding of the damage and failure mechanisms occurring in these components through experimental test campaigns and associated numerical simulations. These experimental tests have been performed at Onera using different classical measurement techniques (LVDT sensor, strain gauges…) and digital image correlation (DIC). The additional information provided by DIC allows (i) to validate the boundary conditions of the tests, (ii) to cross-check the measurements with other techniques, (iii) to improve the understanding of the physical mechanisms and (iv) to validate the predictions of the finite element simulations

Carrier dynamics in semiconductor nanowires studied using optical-pump terahertz-probe spectroscopy

June 15-19, 2015International audienceno abstrac