Fabrication of carbon nanotube-emitters on Ag-Cu alloy film by thermal welding.

A field emission electron source was fabricated on a Si substrate using Ag-Cu alloy (ACa) and carbon nanotubes (CNTs). The ACa was adopted as a binder material due to its excellent electrical conductivity, oxidation stability, and suitable melting point (783 degrees C). The surface morphology of the ACa-film was improved by introducing an Nb layer as an adhesion layer between the ACa-film and the Si substrate. The ACa-film thickness was varied from 100 to 500 nm. The spray method was employed to deposit a CNT film on the ACa/Nb/Si substrate for large area fabrication. After annealing the substrate at 700 degrees C for 10 min, the CNT film was tightly welded on the ACa-films, and the CNT-emitters fabricated on the 400-nm-thick ACa-film exhibited high current density and stability with a low turn-on voltage. It is worth noting that ACa could be applied to the glass substrate because the CNT-emitters fabricated at 500 degrees C exhibited good field emission characteristics.

Synthesis of bandgap-controlled semiconducting single-walled carbon nanotubes.

Bandgap-controlled semiconducting single-walled carbon nanotubes (s-SWNTs) were synthesized using a uniquely designed catalytic layer (Al(2)O(3)/Fe/Al(2)O(3)) and conventional thermal chemical vapor deposition. Homogeneously sized Fe catalytic nanoparticles were prepared on the Al(2)O(3) layer and their sizes were controlled by simply modulating the annealing time via heat-driven diffusion and subsequent evaporation of Fe at 800 degrees C. Transmission electron microscopy and Raman spectroscopy revealed that the synthesized SWNTs diameter was manipulated from 1.4 to 0.8 nm with an extremely narrow diameter distribution below 0.1 nm as the annealing time is increased. As a result, the bandgap of semiconducting SWNTs was successfully controlled, ranging from 0.53 to 0.83 eV, with a sufficiently narrow energy distribution, which can be applied to field-effect transistors based on SWNTs.