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The growth mechanism and dislocation behavior of AlN on monolayer hBN materials without/with O2 plasma treatment by MOCVD.

h i g h l i g h t sEcosystem respiration and its components were mainly controlled by temperature. Q 10 values varied widely with time and among ecosystem respiratory components. Summer flood duration could largely alter drawdown period carbon sink intensity. a r t i c l e i n f o a b s t r a c tLittle is known about the components of ecosystem respiration from a subtropical littoral wetland with dramatic annual inundation dynamics. In this study, we investigated ecosystem respiration and its components in a Poyang lake Carex meadow during the drawdown periods from May 2009 to June 2011. Both ecosystem respiration and its components showed clear temporal variation pattern, with temperature being the dominant control. Ecosystem respiration ranged from 98.01 to 1359.25 mg CO 2 m À2 h À1. Shoot and root respiration contributed approximately 36% and 26% to the ecosystem respiration, respectively, whereas microbial respiration accounted for 38% of the ecosystem respiration. The ratio of total soil respiration to ecosystem respiration varied from 0.45 to 0.90, depending on growing season stages. Their Q 10 values ranged from 1.72 to 2.51, with the maximum for shoot respiration and the minimum for microbial respiration. In addition, the Q 10 values varied with time and among ecosystem respiratory components and hence could not be treated as a constant. None of the respiration measurements was significantly related to soil moisture, suggesting that soil moisture was not a limiting environmental factor for respiratory activity during the drawdown periods in this meadow. The Carex meadow acted as strong carbon sink during the drawdown periods due to double growing seasons, but the previous summer flood duration could substantially alter carbon sink intensity in the following drawdown period. The total carbon sink of the littoral zone of Poyang Lake during drawdown periods was estimated to be 0.17e0.59 Tg C yr À1.

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We experimentally investigated the possibility of using multilayer graphene to solve large mismatch problems between sapphire and nitride and further studied the effects of a multilayer graphene interlayer on the optical and electrical properties of LEDs. For the subsequent growth of 3-µm-thick GaN on AlN, multilayer graphene helps release stress and effectively removes cracks. In addition, multilayer graphene increases the diffraction of the substrate surface as determined from the increase in optical transmittance spectra in the wavelength range of 400–900 nm. Although the crystalline quality of GaN with multilayer graphene is slightly decreased, LEDs grown on multilayer graphene still show a higher output power than those grown on conventional sapphire. The present findings showed that the multilayer graphene layer is attractive as a potential substrate for the epitaxial growth of III–nitride to reduce stress and it could improve back light extraction as a rough layer to increase external quantum efficiency.

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The direct coating of 2D hexagonal boron nitride (h‐BN) on insulating solid glass will endow glass with advanced properties, thus offering killer applications of the new type hybrid of h‐BN glass. However, daunting challenges still remain regarding the direct growth methodology of h‐BN on glass. Herein, a catalyst‐free chemical vapor deposition route for the direct synthesis of 5 in. uniform h‐BN thin films on functional quartz and sapphire glass is developed. The optical transparency, surface wetting, and thermal conductivity of glass are readily tailored by varying the deposited h‐BN thicknesses from monolayer to over 20 layers. Encouragingly, the as‐obtained h‐BN/sapphire glass can serve as a stress‐releasing substrate for the van‐der‐Waals epitaxial growth of AlN functional layers, as well as a thermal conductive template for constructing high‐performance deep‐ultraviolet light‐emitting diodes. This work hereby provides a brand new direction for the application of h‐BN glass in next‐generation solid‐state lighting devices.

Crack-free crystalline AlN film was synthesized on two-dimensional multilayer hexagonal BN (h-BN) by metal organic vapor phase epitaxy (MOVPE). The multilayer h-BN was directly grown on sapphire substrates in wafer scale by MOVPE, with a thickness of 2.9 nm. The AlN film grown on the h-BN/sapphire presented a smooth surface. We further realized the exfoliation of AlN film utilizing the weak bonds within h-BN layers. Moreover, the AlGaN-based deep-ultraviolet light-emitting diodes grown on the AlN/h-BN/sapphire template exhibited obvious emissions at 281 nm. It is promising that the multilayer h-BN will pave the way to obtain transferable high-efficiency devices with wafer scale.