STEM analysis of deformation and B distribution in nanosecond laser ultra-doped Si1−x_{1-x} Bx_x

We report on the structural properties of highly B-doped silicon (> 2 at. %) realised by nanosecond laser doping. We investigate the crystalline quality, deformation and B distribution profile of the doped layer by STEM analysis followed by HAADF contrast studies and GPA, and compare the results to SIMS analyses and Hall measurements. When increasing the active B concentration above 4.3 at.%, the fully strained, perfectly crystalline, Si:B layer starts showing dislocations and stacking faults. These only disappear around 8 at.% when the Si:B layer is well accommodated to the substrate. When increasing B incorporation, we increasingly observe small precipitates, filaments with higher active B concentration and stacking faults. At the highest concentrations studied, large precipitates form, related to the decrease of active B concentration. The structural deformation, defect type and concentration, and active B distribution are connected to the initial increase and subsequent gradual loss of superconductivity

Transcriptome 3′end organization by PCF11 links alternative polyadenylation to formation and neuronal differentiation of neuroblastoma

In gene regulation, diversification at the transcriptome 3′end is linked to differentiation and dedifferentiation. Here, the authors discover extensive transcriptome 3′end-alterations in neuroblastoma, regulated by PCF11, and provide an interactive data repository of transcriptome-wide alternative polyadenylation

Qualitative and quantitative assessments of the growth of (Al,Ga) As-GaAs heterostructures by in situ ellipsometry

Fast ellipsometers have made feasible real-time assessment of heterostructure growth in a vapour phase ambient. A fast ellipsometer/MO-VPE experimental system is described and the possibilities of in situ ellipsometry are investigated in the case of GaAs-(Al, Ga)As structure growth : qualitative assessment in real-time and quantitative assessment (growth rate, composition determination and transition width) by experimental data processing after growth.Le développement d'ellipsomètres automatiques a permis la caractérisation en temps réel de la croissance d'hétérostructures, dans l'environnement haute température et haute pression des réacteurs d'épitaxie en phase vapeur. On décrit la mise en œuvre et l'utilisation d'un ellipsomètre automatique associé à un système d'épitaxie aux organométalliques. L'application de l'ellipsométrie in situ au contrôle en temps réel de la croissance d'hétérostructures est ensuite décrite. Enfin, on montre qu'une analyse a posteriori des mesures in situ permet une caractérisation détaillée du profil de composition et en particulier des interfaces entre films de compositions différentes

Effect of the p

The degradation behaviour of two InGaAs/AlGaAs laser structures differing only in the Zn doping concentration of the p+ GaAs contact layer has been compared. The ageing tests used in this comparison are performed on lasers with Anti-Reflection (AR) coatings on both facets, so as to increase the carrier density in the quantum well and the gradual degradation rate. This kind of ageing test has been discussed in a previous paper, where a possible effect of Zn diffusion was suspected. The defects generated during ageing are studied by Low Temperature (80 K)—Spectrally Resolved Cathodo-Luminescence (LT-SRCL), Cathodo-Luminescence Imaging (CLI) and Transmission Electron Microscopy (TEM). The impact of the acceptor concentration in the contact layer is thus clarified

Intégration de microcristaux de GaAs sur Si(100) sans domaines d'antiphase ni dislocation

National audienc

Intégration de microcristaux de GaAs sur Si(100) sans domaines d'antiphase ni dislocation

National audienc