10 research outputs found

    Optimizing n-type doping of ZnGeN2 and ZnSiN2

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    Anisotropic-strain-enhanced hole mobility in GaN by lattice matching to ZnGeN2_2 and MgSiN2_2

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    The key obstacle toward realizing integrated gallium nitride (GaN) electronics is its low hole mobility. Here, we explore the possibility of improving the hole mobility of GaN via epitaxial matching to II-IV nitride materials that have recently become available, namely ZnGeN2_2 and MgSiN2_2. We perform state-of-the-art calculations of the hole mobility of GaN using the ab initio Boltzmann transport equation. We show that effective uniaxial compressive strain of GaN along the [11ˉ00][1\bar{1}00] by lattice matching to ZnGeN2_2 and MgSiN2_2 results in the inversion of the heavy hole band and split-off hole band, thereby lowering the effective hole mass in the compression direction. We find that lattice matching to ZnGeN2_2 and MgSiN2_2 induces an increase of the room-temperature hole mobility by 50% and 260% as compared to unstrained GaN, respectively. Examining the trends as a function of strain, we find that the variation in mobility is highly nonlinear; lattice matching to a hypothetical solid solution of Zn0.75_{0.75}Ge0.75_{0.75}Mg0.25_{0.25}Si0.25_{0.25}N2_2 would already increase the hole mobility by 160%

    Optimizing n

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    Directed Branch Growth in Aligned Nanowire Arrays

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    Branch growth is directed along two, three, or four in-plane directions in vertically aligned nanowire arrays using vapor–liquid–solid glancing angle deposition (VLS-GLAD) flux engineering. In this work, a dynamically controlled collimated vapor flux guides branch placement during the self-catalyzed epitaxial growth of branched indium tin oxide nanowire arrays. The flux is positioned to grow branches on select nanowire facets, enabling fabrication of aligned nanotree arrays with L-, T-, or X-branching. In addition, a flux motion algorithm is designed to selectively elongate branches along one in-plane axis. Nanotrees are found to be aligned across large areas by X-ray diffraction pole figure analysis and through branch length and orientation measurements collected over 140 μm<sup>2</sup> from scanning electron microscopy images for each array. The pathway to guided assembly of nanowire architectures with controlled interconnectivity in three-dimensions using VLS-GLAD is discussed

    Genome-wide association study identifies novel genetic variants contributing to variation in blood metabolite levels

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    Metabolites are small molecules involved in cellular metabolism, which can be detected in biological samples using metabolomic techniques. Here we present the results of genome-wide association and meta-analyses for variation in the blood serum levels of 129 metabolites as measured by the Biocrates metabolomic platf
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