Data Sharing and Research on Peer Review: A Call to Action

While recent surveys show that most stakeholders recognise the importance of peer review to the publication process, there is a lack of systematic research on the topic. In a period of hyper-competition for resources, with perverse incentives that lead to academic capitalism and a \u201cpublish or perish\u201d mentality, the lack of robust and cumulative research on approaches, models and practices of peer review can slow down efforts towards fostering research integrity and the credibility of scholarly communication. A major challenge in studying peer review systematically is the lack of available data. While data sharing in scientific research has made relevant progress in certain fields, the lack of infrastructures to promote the sharing of peer review data among publishers, journals and academic scholars, the challenges posed by privacy and data protection legislation, and the perceived lack of incentives for publishers, learned societies and journals to share data, have all hampered efforts in this important domain. While public authorities, learned societies and publishers may face different priorities, incentives and obstacles regarding data sharing, the time has come to call to action all stakeholders who play a part in this field. In this paper, we argue that an infrastructure for data sharing is needed to stimulate independent, collaborative, public research on peer review and we suggest measures and initiatives to set up a collaborative effort towards this goal

InGaN islands and thin films grown on epitaxial graphene

International audienceIn this work is studied the growth of InGaN on epitaxial graphene by molecular beam epitaxy. The nucleation of the alloy follows a three-dimensional (3D) growth mode, in the explored temperature range of 515-765°C, leading to the formation of dendrite-like islands. Careful Raman scattering experiments show that the graphene underneath is not degraded by the InGaN growth. Moreover, lateral displacement of the nuclei during an atomic force microscopy scan demonstrate weak bonding interactions between InGaN and graphene. Finally, a longer growth time of the alloy gives rise to a compact thin film in partial epitaxial relationship with the SiC underneath the graphene

Remote epitaxy using graphene enables growth of stress-free GaN

International audienceThe properties of group III-Nitrides (III-N) such as a large direct bandgap, high melting point, and high breakdown voltage make them very attractive for optoelectronic applications. However, conventional epitaxy on SiC and sapphire substrates results in strained and defective films with consequently poor device performance. In this work, by studying the nucleation of GaN on graphene/SiC by MOVPE, we unambiguously demonstrate the possibility of remote van der Waals epitaxy. By choosing the appropriate growth conditions, GaN crystals can grow either in-plane misoriented or fully epitaxial to the substrate. The adhesion forces across the GaN and graphene interface are very weak and the micron-scale nuclei can be easily moved around. The combined use of x-ray diffraction and transmission electron microscopy demonstrate the growth of stress-free and dislocation-free crystals. The high quality of the crystals was further confirmed by photoluminescence measurements. First principles calculations additionally highlighted the importance of the polarity of the underlying substrate. This work lays the first brick towards the synthesis of high quality III-N thin films grown via van der Waals epitaxy

Detekce N-Te vazeb v dusíkem dopovaných amorfních phase change slitinách na bázi GeTe pomocí XANES spektroskopie N K-hrany a jejich dopad na krystalizaci

Using N K-edge XANES studies, we demonstrate a noticeable difference in local structure around the nitrogen atoms in as-deposited amorphous and annealed N-doped GeTe-based phase change alloys. The pronounced changes appear as a approximate to 2 eV shift in the absorption edge to higher photon energies and the overall shape of the XANES spectrum. Comparison of the experimental XANES spectrum of the as deposited amorphous phase with ab-initio XANES simulations discloses that the as-deposited phase mainly consists of the NGe3 and the NTe3 pyramidal units in approximately equal concentration. When annealed, NTe3 units gradually rebond to the NGe3 units and at the same time N atoms diffuse through the amorphous phase to form the GexNy aggregates. Upon long-standing annealing at 400 degrees C a compact interlayer of Ge3N4 is formed in the crystalline phase.Zjistili jsme pomocí XANES studií N K-hrany značný rozdíl v lokálním uspořádání kolem atomů dusíku v čerstvě připravených amorfních a žíhaných dusíkem dopovaných slitinách na bázi GeTe. Zřetelné změny se objevují v podobě posunu v absorpční hraně o 2 eV do vyšších fotonových energií a celkovým tvarem XANES spektra. Porovnání experimentálního XANES spektra deponované amorfní fáze s ab-initio XANES simulacemi odhaluje, že deponovaná amorfní fáze se převážně skládá z NGe3 a NTe3 pyramidálních jednotek v přibližně shodném koncentraci. Během žíhání se NTe3 jednotky postupně přetvářejí do NGe3 jednotek a současně atomy dusíku difundují skrz amorfní fázi za tvorby GexNy shluků. Při dlouhodobém žíhání na teplotu 400°C se vytváří v krystalické fázi mezivrstva Ge3N4

Charge transfers and charged defects in WSe 2 /graphene-SiC interfaces

International audienceWe report on Kelvin Probe Force Microscopy (KPFM) and Density Functional Theory (DFT) investigations of charge transfers in vertical heterojunctions between tungsten diselenide (WSe2) layers and graphene on silicon carbide substrates. The experimental data reveal the existence of an interface dipole, which is shown by DFT to originate from the neutralization of the graphene n-doping by an electron transfer towards the transition metal dichalcogenide (TMD) layer. The relative vacuum level shift probed by KPFM between the TMD and the substrate stays constant when passing from monolayer to bilayer graphene, which confirms that the Schottky-Mott model can be rigorously applied to these interfaces by taking into account the charge transfer from the substrate to the TMD. DFT calculations show that the first TMD layer absorbs almost all the excess charges contained in the graphene, and that the second TMD layer shall not play a significant role in the electrostatics of the system. Negatively charged defect at the TMD edges contribute however to the electrostatic landscape probed by KPFM on both TMD layers