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31.
Cheng Y Wang M Borghs G Chen H 《Langmuir : the ACS journal of surfaces and colloids》2011,27(12):7884-7891
In this study, gold nanoparticles (GNP) were stabilized for the first time as dimers by a conducting polymer (CP). The morphology of kissing particles was examined by high-resolution transmission electronic microscopy (HRTEM). The broad-band localized surface plasmon resonance (LSPR) tunable by solvent variation and molecular binding was demonstrated by UV-vis measurement. The sensitivity of the longitudinal LSPR to the surrounding media or the binding of a biomolecule was 6 times higher than that of the transversal LSPR. A homogeneous bioassay was directly developed from the highly stable GNP-CP dimers with LSPR as prober, and protein sensing with detection limit well below 100 ng/mL was achieved. 相似文献
32.
R.R. Lieten O. Richard S. Degroote M. Leys H. Bender G. Borghs 《Journal of Crystal Growth》2011,314(1):71-75
Early efforts to grow GaN layers on germanium substrates by plasma assisted molecular beam epitaxy led to GaN domains, rotated by 8° relative to each other. Increased insight in the growth of GaN on germanium resulted in the suppression of these domain and consequently high quality layers. In this study the interface of these improved layers is investigated with transmission electron microscopy. The GaN layers show high crystal quality and an atomically abrupt interface with the Ge substrate. A thin, single crystalline Ge3N4 layer is observed in between the GaN layer and Ge substrate. This Ge3N4 layer remains present even at growth temperatures (850 °C) far above the decomposition temperature of Ge3N4 in vacuum (600 °C). Triangular voids in the Ge substrate are observed after growth. Reducing the Ga flux at the onset of GaN growth helps to reduce the triangular defect size. This indicates that the formation of voids in the Ge substrate strongly depends on the presence of Ga atoms at the onset of growth. However complete elimination was not achieved. The formation of voids in the germanium substrate leads to diffusion of Ge into the GaN layer. Therefore we examined the diffusion of Ge atoms into the GaN layer and Ga atoms into the Ge substrate. It was found that the diffusion of Ge into the GaN layer and Ga into the Ge substrate can be influenced by the growth temperature but cannot be completely suppressed. Our results suggest that Ga atoms diffuse through small imperfections in the Ge3N4 interlayer and locally etch the Ge substrate, leading to the diffusion of Ga and Ge atoms. 相似文献