Papers by Author: J.W. Lu

Abstract: The field electron emission from carbon nanotube films on polycrystalline diamond films was investigated. The carbon nanotubes and diamond films on Si substrates were prepared by a conventional hot filament chemical vapour deposition. The films obtained were characterized by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 10-6 Pa.. The experimental results showed that the field emission behaviours of carbon nanotubes/diomond films structure have greatly been improved as compared with carbon nanotubes and diamond films, respectively. A turn-on field of 1.0 V/µm and a maximum current of 500 µA at 1.5 V/µm were observed, which were lower than those of carbon nanotubes and polycrystalline diamond films, respectively. This improvement was attributed to the tip shape of sample surface, which provided an additional local increase in electric field at the tube ends.

Abstract: The piezoresistive effect in iodine-doped carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the gauge factor for I-doped and undoped carbon nanotube films under 500 microstrain was about 350 and 65 respectively at room temperature, exceeding that of polycrystalline silicon (30) at 35°C. The origin of the piezoresistivity in the films may be ascribed to a strain-induced change in the band gap for the doped tubes and the intertube contact resistance and defects for the undoped tubes.

Abstract: The electron field emission from carbon nanotubes on nanocrystalline diamond films was investigated. Carbon nanotubes and nano-diamond films were deposited on Si substrates by hot filament chemical vapor deposition. The experimental results showed that the carbon nanotubes on nanostructured films exhibited a lower value of the turn-on electric field than those of carbon nanotubes and nano-diamond. It was found that the turn-on field of nanotubes on nano-diamond was about 0.9V/μm, which was lower than those of carbon nanotubes and nano-diamond.