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International audience; Low-temperature plasma enhanced atomic layer deposition (PE-ALD) was successfully used to grow silicon (Si) doped amorphous and microcrystalline gallium phosphide (GaP) layers onto p-type Si wafers for the fabrication of n-GaP/p-Si heterojunction solar cells. PE-ALD was realized at 380 °C with continuous H2 plasma discharge and the alternate use of phosphine and trimethylgallium as sources of P and Ga atoms, respectively. The layers were doped with silicon thanks to silane (SiH4) diluted in H2 that was introduced as a separated step. High SiH4 dilution in H2 (0.1%) allows us to deposit stoichiometric GaP layers. Hall measurements performed on the GaP:Si/p-Si structures reveal the presence of an n-type layer with a sheet electron density of 6–10 × 1013 cm−2 and an electron mobility of 13–25 cm2 V−1 s−1 at 300 K. This is associated with the formation of a strong inversion layer in the p-Si substrate due to strong band bending at the GaP/Si interface. GaP:Si/p-Si heterostructures exhibit a clear photovoltaic effect, with the performance being currently limited by the poor quality of the p-Si wafers and reflection losses at the GaP surface. This opens interesting perspectives for Si doped GaP deposited by PE-ALD for the fabrication of p-Si based heterojunction solar cells.

International audience; Thin layers of μc-GaP and a-GaP grown on n- type silicon wafers by plasmaenhanced atomic layer deposition at 380 C are characterized by space charge capacitance techniques, C-V profiling and deep level transient spectroscopy (DLTS). Two defect levels with activation energies of 0.30 eV and 0.80 eV were detected by DLTS in the μc-GaP/n-Si structure. Measurements performed on Schottky barriers formed on n-Si after selective etching of the GaPlayer did not reveal any defect level meaning that the observed defects in the μc-GaP/n-Si structure are related to μc-GaP layer.

Resume Introduction Les instillations endovesicales de BCG constituent le traitement de reference des TVNIM de risque intermediaire et eleve. Un traitement d’entretien est fortement recommande, neanmoins la frequence des effets secondaire responsable de l’arret du traitement d’entretien chez plus de quatre patients sur cinq avant la troisieme annee pourrait justifier une diminution voire un espacement des instillations. L’objectif de l’etude URO-BCG-4 etait l’evaluation d’un nouveau schema d’entretien par instillations endovesicales de BCG associant une diminution de dose (un tiers de dose) mais aussi une diminution du nombre d’instillation par cycle (deux ou trois). Patients et methodes Etude multicentrique du CCAFU (12 centres hospitalo-universitaires), randomisee, prospective, comparant le schema de reference de BCG-therapie d’entretien au un tiers de dose usuelle (groupe I) a un schema associant un tiers de dose et diminution du nombre d’instillations par cycle (deux au lieu de trois) (groupe II). Nous presentons les resultats preliminaires a un an de ce programme hospitalier de recherche clinique (2003-081 CHU de Rouen Promoteur). Resultats Le taux de recidive tumorale etait respectivement de 9 et 7 % ( p = 0,678) dans les groupes I et II. Le taux de progression tumorale etait de 3 et 2,8 % dans les groupes I et II ( p = 1). La tolerance des instillations endovesicales de BCG evaluee selon la classification OMS (Geneve 1979) etait comparable dans les deux groupes. Conclusion La diminution de la dose de BCG (un tiers de dose) et la modification du nombre et du rythme des instillations n’a pas modifie le taux de survie sans recidive tumorale. La toxicite des instillations endovesicales de BCG etait identique dans les deux groupes. L’utilisation de la classification OMS a montre ses limites dans l’etude des effets secondaires du BCG car trop complexe et souvent non exhaustive. Le taux de progression musculaire etait comparable dans les deux groupes neanmoins un recul clinique plus important est necessaire.

International audience; Extraordinary Hall Effect (EHE) based original concepts of a reconfigurable logic gate and a multibitlogic comparator are presented. They exploit the EHE voltage that develops on cross cells connectedin series that has no size limitation down to the nanometer scale. Experimental demonstrationsare performed on both micro- and nanometer lateral size crosses made of ferrimagnetic TbCo alloy.The simplicity of the device architecture and its robustness make it advantageous when comparedwith existing systems.

Background HIV-specific CD8 T cells responses rely on the recognition of peptide-MHC-I complexes by cognate T cell receptors. HIV-derived MHC-I epitopes result from the degradation of viral proteins by the cellular processing machinery including proteasomes and aminopeptidases. Interferon gamma changes proteasome composition and peptidase activities. We hypothesize that HIV infection might affect the expression or activities of the antigen processing machinery, either through a direct effect of the virus or indirectly through cellular activation or from the release of cytokines by surrounding infected cells.

Background Whether HIV-infectable subsets, such as CD4 T cells, monocytes, macrophages and dendritic cells (DCs), have equivalent capacity to produce and present MHC-I restricted epitopes to HIV-specific CD8 T cells is unknown. MHC-I epitopes are processed by an intracellular degradation pathway involving multiple proteases. In this study we analyzed the effect of toll-like receptor (TLR) agonist-mediated maturation on the processing and presentation of HIV antigens in monocyte-derived DCs and macrophages.

International audience; The transport mechanisms through MgO ultrathin layers (0.5-1.2 nm) deposited on n-type doped GaAs(001) layers have been studied. In order to favor field emission (FE) across the junctions, a high doping concentration layer in vicinity of the semiconductor surfaces has been included. Varying doping concentration of the underlying GaAs layer we find that the dominant transport mechanism is either the variable-range hopping mechanism or a thermionic emission-like process instead of the FE process. The observation of such mechanisms can be explained by the fact that during the MgO deposition, defect states are introduced in the semiconductor band gap.

International audience; We report on ballistic electron-emission spectroscopy on high-quality Au(110)/GaAs(001) and Fe(001)/GaAs(001) Schottky contacts. For the Au(110)/GaAs(001) interface, the ballistic current is characterized by a strong electron injection in the L valley of the GaAs conduction band. This remarkable spectroscopic feature is absent for the Fe(001)/GaAs(001) interface. These observations are explained by the different electronic structures in the two metal layers, assuming conservation of the electron transverse momentum at the metal/semiconductor epitaxial interfaces. Conversely, this comparative study suggests that the technique can be used for the analysis of local electronic states propagating in the metal films.

International audience; The electrical properties of Au/MgO/n-GaAs(001) tunnel structures have been investigated with capacitance-voltage and current-voltage measurements at room temperature with various MgO thicknesses between 0.5 and 6.0nm. For an oxide thickness higher than 2nm and for low bias voltages, the voltage essentially drops across the oxide and the structure progressively enters the high-current mode of operation with increasing reverse bias voltage, the property sought in spin injection devices. In this mode, we demonstrate that a large amount of charge accumulates at the MgO/GaAsinterface in interface traps located in the semiconductor band gap.

Background HIV-1 Nef is a multifunctional protein frequently targeted by host CD8+ T cell responses in early and chronic phases of HIV-1 infection. In vivo reversions of CTL escape mutations within Nef have been reported, suggesting a possible impact of immune-selected mutations in Nef on viral fitness. The goal of this work was to determine whether CD8+ T cell selected mutations in regions outside of Gag, such as in Nef, also impair viral replication and may thus contribute to early immune control of HIV-1.