For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10(-8) Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.

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A major attraction of polariton lasers is the potential to achieve much lower thresholds than in conventional photon lasers, since no population inversion is required. Achieving low threshold operation is vital for future organic polariton devices, both to enhance stability by reducing photoinduced degradation and to reduce the number of charge carriers required to achieve an electrically pumped polariton laser. However, the cavity polariton lasing thresholds from organic semiconductors in planar microcavities reported to date [5,6] are higher than 300 µJ cm −2 in incident excitation density and also higher than photon lasing thresholds from the same class of materials. There is therefore a need for new materials that can achieve low threshold polariton lasing. In this paper, we report polariton lasing using an oligofluorene in a planar dielectric microcavity giving an order of magnitude reduction in threshold to 17 µJ cm −2 . This corresponds to an absorbed energy density of 11.7 µJ cm −2 . It is also comparable with the lowest plasmon exciton polariton lasing threshold of 18 µJ cm −2 , obtained from a dye on a laterally patterned nanoparticle array. [9] To achieve this low-threshold operation, we select a material with high photoluminescence quantum yield (PLQY) and oscillator strength, pentafluorene, and introduce a buffer layer in the top mirror to retain the high PLQY in the dielectric microcavity. We observe the key features of polariton lasing including a nonlinear emission intensity beyond a threshold excitation density, a drop in the spectral linewidth of emission, and increase in directionality of emission. An associated collapse in the spatial distribution of emission and macroscopic coherence are also observed. In contrast with photon lasing, accumulation of population is at the bottom of the lower polariton branch. We also observe a drop in polariton lasing threshold by simultaneously increasing the radiative component of the lower polariton mode through negative detuning and the proximity to the spectral gain window of pentafluorene. This suggests that the population mechanism dominating the lower polariton branch is largely radiative. [10] Oligofluorenes are a class of materials associated with high exciton binding energy and absorption oscillator strength. [11,12] They are also associated with very short radiative lifetimes [11,13] and high photoluminescence (PL) quantum yield. [14] Oligofluorene films have been reported not to show green excimer Organic semiconductor materials are widely studied for light emission and lasing due to their ability to tune the emission wavelength through chemical structural modification and their relative ease of fabrication. Strong light-matter coupling is a promising route toward a coherent light source because it has the potential for polariton lasing without population inversion. However, the materials studied so far have relatively high thresholds for polariton lasing. Here, the suitability of pentafluorene for strong coupling and low threshold polariton lasi...

Abstract. Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH 4 emissions and ecosystem respiration (R eco ) from five coastal wetlands in the Liaohe Delta, Northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH 4 sinks whereas the Phragmites wetlands and the rice paddy were net CH 4 sources emitting 1.2-6.1 g CH 4 m −2 yr −1 . The Phragmites wetlands emitted the most CH 4 per unit area and the most CH 4 relative to CO 2 . The main controlling factors for the CH 4 emissions were water table, temperature, soil organic carbon and salinity. The CH 4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH 4 emissions, and emission rates were consistently low (< 1 mg CH 4 m −2 h −1 ) at soil temperatures < 18 • C. At salinity levels > 18 ppt, the CH 4 emission rates were always low (< 1 mg CH 4 m −2 h −1 ) probably because methanogens were out-competed by sulphate-reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH 4 as CH 4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH 4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities.