Suchergebnisse

We report on identification and control of important nonradiative recombination centers in GaNP coaxial nanowires (NWs) grown on Si substrates in an effort to significantly increase light emitting efficiency of these novel nanostructures promising for a wide variety of optoelectronic and photonic applications. A point defect complex, labeled as DD1 and consisting of a P atom with a neighboring partner aligned along a crystallographic ⟨111⟩ axis, is identified by optically detected magnetic resonance as a dominant nonradiative recombination center that resides mainly on the surface of the NWs and partly at the heterointerfaces. The formation of DD1 is found to be promoted by the presence of nitrogen and can be suppressed by reducing the strain between the core and shell layers, as well as by protecting the optically active shell by an outer passivating shell. Growth modes employed during the NW growth are shown to play a role. On the basis of these results, we identify the GaP/GaNyP1–y/GaNxP1–x (x < y) core/shell/shell NW structure, where the GaNyP1–y inner shell with the highest nitrogen content serves as an active light-emitting layer, as the optimized and promising design for efficient light emitters based on GaNP NWs. ; Funding Agencies|Swedish Research Council [621-2010-3815]; U.S. National Science Foundation [DMR-0907652, DMR-1106369]; Royal Government of Thailand

The political project on bioeconomy strives to address multiple societal aspirations, namely combine economic growth with environmental sustainability in some socially acceptable manner. The contradictions between the goals and the concrete plans to increase production, processing, and consumption of forest biomass in Europe have however raised sustainability concerns within and beyond its borders. While political actors articulate such contradictions differently and compete for traction for their viewpoints in the public discourse, little is known about how citizens of urban areas perceive this discourse. Conceptualising perception as a multidimensional construct, data from eight European university cities (Bordeaux, Bratislava, Freiburg, Helsinki, Padua, St. Petersburg, Uppsala, Vienna) are statistically analysed to explore its dimensions, the communities of like-minded citizens forming across those dimensions, and the traits associating with membership in each such community. Five communities across six dimensions from biocentrism through distributional aspects to adherence to political goals are identified: adherent-environmentalist, adherent-governmentalist, critical-reformist, critical-agriculturalist, and indifferent. City of residence and perceived familiarity with bioeconomy clearly interact with perception. There is however considerable variation in communities within and across the eight cities, suggesting deeper social tension beyond the public discourse. Much of the within-community variation remains unexplained, though, calling for more work locally. Implications for forest policy are derived. ; Peer reviewed