Amino-functionalized graphene quantum dots (af-GQDs) with discrete molecular weights and specific edges were self-limitedly extracted from oxidized graphene sheet. Their optical properties can be precisely controlled only by the selective and quantitative functionalization at the edge sites. The af-GQDS exhibit bright colorful fluorescence under a single-wavelength excitation.

Silicon carbide (SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for next-generation electronic devices. Careful consideration of the thermal conditions in which SiC [0001] is grown has resulted in improvements in crystal diameter and quality: the quantity of macroscopic defects such as hollow core dislocations (micropipes), inclusions, small-angle boundaries and long-range lattice warp has been reduced. But some macroscopic defects (about 1-10 cm(-2)) and a large density of elementary dislocations (approximately 10(4) cm(-2)), such as edge, basal plane and screw dislocations, remain within the crystal, and have so far prevented the realization of high-efficiency, reliable electronic devices in SiC (refs 12-16). Here we report a method, inspired by the dislocation structure of SiC grown perpendicular to the c-axis (a-face growth), to reduce the number of dislocations in SiC single crystals by two to three orders of magnitude, rendering them virtually dislocation-free. These substrates will promote the development of high-power SiC devices and reduce energy losses of the resulting electrical systems.

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We investigated the growth process of carbon nanowalls (CNWs) on a SiO2 substrate by microwave plasma-enhanced chemical vapor deposition (MPECVD). It is revealed that the CNWs are grown at the fine-textured structure on the SiO2 and the growth process does not require the catalyst. The CNW initially has a semicircular shape. The height, thickness, and mesh size increase with growth time. It is found that the height of CNWs as a function of time obeys the square root law. Extremely high growth rate, approximately 10 µm/h, is achieved, in contrast to previous studies.

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