Self-induced preparation of TiO2 nanowires by chemical vapor deposition.

High-density single-crystalline TiO 2 nanowires are successfully fabricated on a TiSi 2 layer using a new self-induced catalyst-free method by APCVD. The results show that the high aspect ratio nanowires with diameters of 20–50 nm and lengths of about 3 μm are obtained on a TiSi 2 layer at 720 °C. The length of TiO 2 nanowires increases with the preparation time until Ti is exhausted. The nanowires shape changes with the concentration of O 2 and temperature. When the temperature is above 720 °C or the flux of O 2 is over 6 sccm, the density and length of nanowires decrease under the combined effect of the increasing lateral surface diffusion and longitudinal growth. The formation of TiO 2 nanowires comes along with the consumption of TiSi 2 , TiO 2 nanowires grow along the [001] direction of the tetragonal rutile TiO 2 crystal from the bottom, with the tip being pushed upwards. The growth process is proposed which is consistent with our experiment results. [ABSTRACT FROM AUTHOR]