Technical Institute of Physics and Chemistry, Chinese Academy of Science, Beijing 100190, PR China.
Nanoscale Res Lett. 2011 Jul 15;6(1):454. doi: 10.1186/1556-276X-6-454.
Colloidal cubic silicon carbide (SiC) nanocrystals with an average diameter of 4.4 nm have been fabricated by anisotropic wet chemical etching of microsized cubic SiC powder. Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups. UV/Vis absorption and photoluminescence (PL) spectroscopy clearly indicate that water and ethanol colloidal suspensions of the as-fabricated colloidal samples exhibit strong and above band gap blue and blue-green emissions. The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals. The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.
胶体立方碳化硅（SiC）纳米晶体的平均直径为 4.4nm，是通过微尺度立方 SiC 粉末各向异性湿化学刻蚀制备的。傅里叶变换红外光谱显示，这些立方 SiC 纳米晶体含有羧酸、SiH、CH 和 CHx 基团。紫外/可见吸收和光致发光（PL）光谱清楚地表明，所制备的胶体样品的水和乙醇胶体悬浮液显示出强的带隙以上的蓝色和蓝绿色发射。由于水分子与立方 SiC 纳米晶体的极性 Si 端表面的相互作用，立方 SiC 纳米晶体在水和乙醇溶液中表现出不同的表面电荷。这些结果解释了胶体立方 SiC 纳米晶体在水和乙醇中的独特光学特性，并表明量子限制和表面电荷在决定胶体立方 SiC 纳米晶体的光学特性方面起着重要作用。
