Selective beta-SiC/SiO2 core-shell NW growth on patterned silicon substrate

NWs have been synthesized on patterned silicon wafers in a CVD system, using carbon oxide as single precursor and nickel nitrate as catalytic element, in nitrogen or argon atmosphere at 1100 degrees C. The coaxial structure and the crystallinity of the NW core are examined by (scanning) transmission electron microscopy. The patterning of the substrate allows to grow NWs in selected areas only, as imaged by SEM. Cathodoluminescence (CL) panchromatic images of the same areas point out that the light emitted under electron excitation is localized only in the area covered with NWs. The room-temperature CL spectrum has three different components peaked at 2.45 eV, related to the 3C-SiC near-band-edge emission, and at 2.75 and 3.75 eV, that are induced by the triplet and singlet states of oxygen-deficiency centers ODC(II) in silicon dioxide shell.