Properties and characterization of ALD grown dielectric oxides for MIS structures

We report on an extensive structural and electrical characterization of under-gate dielectric oxide insulators Al2O3 and HfO2 grown by Atomic Layer Deposition (ALD). We elaborate the ALD growth window for these oxides, finding that the 40-100 nm thick layers of both oxides exhibit fine surface flatness and required amorphous structure. These layers constitute a base for further metallic gate evaporation to complete the Metal-Insulator-Semiconductor structure. Our best devices survive energizing up to ~3 MV/cm at 77 K with the leakage current staying below the state-of-the-art level of 1 nA. At these conditions the displaced charge corresponds to a change of the sheet carrier density of 3 \times 1013 cm-2, what promises an effective modulation of the micromagnetic properties in diluted ferromagnetic semiconductors.Comment: 8 pages, 5 figures, 14 reference

Effective Mg Incorporation in CdMgO Alloy on Quartz Substrate Grown by Plasma-assisted MBE

The development of CdMgO ternary alloy with a single cubic phase is challenging but meaningful work for technological advancement. In this work, we have grown a series of Cd1-xMgxO ternary random alloys with various Mg concentrations (x = 0, 30, 32, 45, and 55%) on quartz substrate by plasma-assisted molecular beam epitaxy (PA-MBE) technique. The structural investigations of alloys were performed using the X-ray diffraction (XRD) technique. The decreases in average crystallite size and lattice parameters were observed with an increase in Mg content in the alloys. XRD analysis confirms a single cubic phase is obtained for alloy compositions. The elemental and morphological studies were carried out using energy dispersive x-ray (EDX) spectroscopy and atomic force microscope (AFM) technique, respectively. The optical investigation was carried out using UV-Vis spectroscopy. The optical bandgaps were estimated using the Tauc relation and it was varied from 2.34 eV to 3.47 eV by varying the Mg content from zero to 55% in the alloys. The Urbach energy increases from 112 meV to 350 meV which suggests a more disordered localized state with an increase in Mg incorporation in the alloys.Comment: 22 pages, 8 figures, 2 table

MBE grown preferentially oriented CdMgO alloy on m- and c-plane sapphire substrates

Unlike other II-VI semiconductors, CdO-based transparent oxide has great potential application for the fabrication of many optoelectronic devices. In this work, we study the growth of CdxMg1-xO alloys on m- and on c-plane sapphire substrates in Cd-rich to Mg-rich conditions using the plasma-assisted molecular beam epitaxy method. A structural and morphological study of CdMgO random alloys was carried out using X-ray diffraction and Atomic Force Microscope (AFM) techniques whereas composition analysis was done by Energy-dispersive X-ray (EDX) spectroscopy method. The optical properties of thin films were investigated by UV-Vis spectroscopy at room temperature. X-ray analysis confirmed the presence of cubic rock salt structure with CdMgO crystallographic orientation on c-plane sapphire and CdMgO preferential orientation on m-plane sapphire. The surface roughness was measured by the AFM. From the absorption curve, the optical bandgaps were determined using Tauc relation and it was found that the bandgap of films is influenced by the incorporation of Mg2+ ions into the CdO lattice. Bowing parameter was calculated both for samples on m- and c- sapphires.Comment: 19 pages, 11 figure

Faunal Remains: Results by Species

https://orcid.org/0000-0001-7487-2635This book is distributed under the terms of the Creative Commons Attribution + Noncommercial 4.0 license. Copyright is retained by the author(s). The attached file is the published version of the article

Use of Plasmodium falciparum culture-adapted field isolates for in vitro exflagellation-blocking assay

International audienceA major requirement for malaria elimination is the development of transmission-blocking interventions. In vitro transmission-blocking bioassays currently mostly rely on the use of very few Plasmodium falciparum reference laboratory strains isolated decades ago. To fill a piece of the gap between laboratory experimental models and natural systems, the purpose of this work was to determine if culture-adapted field isolates of P. falciparum are suitable for in vitro transmission-blocking bioassays targeting functional maturity of male gametocytes: exflagellation. Plasmodium falciparum isolates were adapted to in vitro culture before being used for in vitro gametocyte production. Maturation was assessed by microscopic observation of gametocyte morphology over time of culture and the functional viability of male gametocytes was assessed by microscopic counting of exflagellating gametocytes. Suitability for in vitro exflagellation-blocking bioassays was determined using dihydroartemisinin and methylene blue. In vitro gametocyte production was achieved using two isolates from French Guiana and two isolates from Cambodia. Functional maturity of male gametocytes was assessed by exflagellation observations and all four isolates could be used in exflagellation-blocking bioassays with adequate response to methylene blue and dihydroartemisinin. This work shows that in vitro culture-adapted P. falciparum field isolates of different genetic background, from South America and Southeast Asia, can successfully be used for bioassays targeting the male gametocyte to gamete transition, exflagellation

Search for the Weak Decay of an H Dibaryon

We have searched for a neutral $H$ dibaryon decaying via $H\to\Lambda n$ and $H\to\Sigma^0 n$. Our search has yielded two candidate events from which we set an upper limit on the $H$ production cross section. Normalizing to the inclusive $\Lambda$ production cross section, we find $(d\sigma_H/d\Omega) / (d\sigma_\Lambda/d\Omega) < 6.3\times 10^{-6}$ at 90% C.L., for an $H$ of mass $\approx$ 2.15 GeV/$c^2$.Comment: 11 pages, 6 postscript figures, epsfig, aps, preprint, revte