The 33 μm thick film vertical structure LEDs without any substrate were fabricated and their free standings were successfully realized by laser lift‐off and HVPE technology. Through the AFM analyses we know that the laser irradiation can causes big damage to the wafer. However, since the 33 μm thick film vertical structure LEDs without any substrate have longer distance between the laser irradiating plane and the quantum well than the the thin film (3‐4 μm) vertical structure LED on Cu or Si substrate, the 33 μm free standing thick film vertical structure LEDs exhibited good electrical and optical characteristics for the less damage on the quantum well caused by the laser lift off process. It has also been proved that the 33 μm thick film vertical structure LEDs without any substrate has lower thermal series resistance than the vertical structure LEDs on 300‐400 μm free standing GaN substrate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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In this study, a waterproof material was used to fabricate microcapsule by interfacial curing reaction to encapsulate an alkaliphilic spore-forming bacterium. The technical feasibility of encapsulated spores and the influence of three kinds of curing agent on the calcium precipitation activity (CPA) of the bacterium were studied. Furthermore, micromorphology of microcapsules was observed by Scanning Electron Microscopy (SEM). Afterwards, the thermal stability and thermolysis temperature were determined by TGA thermal analyzer. Moreover, the CPA of broken/ unbroken microcapsules was evaluated. In addition, water resistance was evaluated by adding microcapsules in the water for 1, 3, 7, 14, 28, and 56 days. Finally, light microscope was applied to trace the self-healing behavior of encapsulated mineralization bacterium in cement paste specimens.The results showed that compared with unbroken microcapsules, higher CPA was achieved by breaking the microcapsule to release the bacterium, suggesting good protection for the encapsulated spores. Three curing agents showed nearly similar influence on the spores, while KH792 performed relatively better, and thus was used to fabricate microcapsule with the core/shell weight ratio being 1:1. Our results also indicated that ER microcapsules could keep unbroken in the water for 2 months. Compared with the specimens without embedded bacterium, the healed crack area of specimens embedded with bacterial microcapsules was monitored, suggesting effective self-healing of concrete crack can be achieved by introducing encapsulated mineralization microorganisms into concrete structures. Therefore, we put forward that this waterproof epoxy resin microcapsules could be potential for the application of self-healing concrete.

Two GaN samples, with and without high temperature (HT)‐AlN interlayer (labelled as sample A and B, respectively) grown by MOCVD on AlN template, were investigated by double‐crystal X‐ray diffraction (DC‐XRD), photoluminescence (PL), and atomic force microscope (AFM) measurements. It was found that the crystal quality of GaN could be greatly improved by the HT‐AlN interlayer. The full width at half maximum (FWHM) of (102) reflection in XRD rocking curve was narrower for sample A than that for sample B. However, the FWHMs of (002) reflections were almost the same for the two samples. In addition, the tilt degree which reflected screw dislocation density was almost the same, while the twist degree which reflected edge dislocation density changed from 0.214° to 0.152° when the HT‐AlN interlayer was used. Both the intensities of (102) reflection in XRD and band edge emission in PL for sample A were stronger too. In the AFM images, the atomic growth steps of sample A were clearer than those of sample B. According to the results of the in situ optical reflectivity spectra and the atomic force microscope (AFM) images, the above results were attributed to the three‐dimensional (3D) growth mode of the HT‐AlN interlayer. The HT‐AlN interlayer may work as a kind of “micro‐area” seed for epitaxial lateral overgrowth (ELOG) resulting in bending some dislocations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)