Abstract
In this work, amorphous silicon oxide nanowires were successfully synthesized by a furnace and its growth mechanism and cathodoluminesce properties were well studied as well. For the synthesis, a Si(100) wafer is used as the solid source for the silicon oxide nanowire growth and the a sputtered platinum thin film ~ 5 nm is used as the catalyst. The growth is achieved under an atmosphere of a mixture of Ar gas with 10% H2 at temperature of 1100°C for 5 hrs. The product is amorphous SiOx nanowires with a diameter of ~40-60 nm and a length of ~hundreds of μm. The growth is confirmed as the solid-liquid-solid mechanism. Then we improved this SLS mechanism to a two-step growth method for a large scale of amorphous SiOx nanowire films. The two-step growth method introduces an oxidation process of the silicon wafer before the SLS growth. Two kinds of nanowires can be obtained by this method: for one is a thick amorphous SiOx nanowire film with smooth and straight nanowires inside and the other is a thinner film with curved and coarsening nanowires. The two-step growth method can provide higher efficiency and more flexibility than the traditional SLS mechanism. In the second part, the cathodoluminescence of these SiOx nanowires were characterized and an intense blue emission at ~2.73 eV was found out with an intensity of more than 20 times than the red emission at ~1.99 eV, which is very different from the bluk or thin film silica. This strong cathodoluminescence can have applications in the nano optoelectronics and in the fundamental research of mesoscopic science as well. At last, we have compared the difference in the cathodoluminescence of the pure and doped silica nanowires and the origin of the defects associating the luminescence were discussed. The manipulation of the doping elements can achieve the modification of the cathodoluminescence and thus provide potential applications in the optoelectronics devices in the future.