Syntheses and photoluminescence properties of SiC nanowires with different colors

Abstract

Abstract Silicon carbide nanowires (SiC NWs) with different colors (green, blue and white) were synthesized by sol-gel carbothermal reduction method. The chemical composition and morphology of SiC NWs were investigated by multiple characterization methods. It shows that both green and blue products are 3C–SiC NWs and the white product is SiC/SiO2 cable-structure NWs. The effects of the SiO2/C molar ratio of raw materials and the reaction temperature on the fabrication of green, blue and white SiC NWs were investigated. It is found that green SiC NWs tend to generate at high temperature (1600 °C) and low SiO2/C molar ratio (1:1). And blue SiC NWs are more likely to form at relatively low temperature (1550 °C) and high SiO2/C molar ratio (2:1). In addition, the white SiC/SiO2 cable-structure NWs were synthesized with high SiO2/C molar ratio and low temperature (1500 °C). The two-step growth mechanism was proposed to interpret the growth process. The photoluminescence properties and band gaps of the nanowires were also investigated. It shows that as the size of SiC reduces into nanometer, its band gap enlarges, which leads to the blue-shift of light emission. The discrepancy in emission spectra was assumed to be related to different thickness of their SiO2 coatings. And the different thickness of SiO2 coatings results in the multicolor discrepancy of SiC nanowires.