Epitaxial growth of asymmetric α-silicon nitride nanocombs

The asymmetric α-Si3N4 nanocombs have been prepared by direct current arc discharge method without the addition of any catalyst or template. The nanocombs are composed of closely packed Si3N4 nanowires, which grow perpendicular to the central axial nanorods in an epitaxial manner. The growth mechanism of the α-Si3N4 nanocombs can be considered as a combination of the vapor–solid mechanism and the secondary epitaxial nucleation process. The photoluminescence spectra of the nanocombs show a strong blue light emission peak at about 424 nm.