High current density nanofilament cathodes for microwave amplifiers

The fabrication of high current density nanofilament cathodes for microwave amplifiers was discussed. Metallic nanowires grown on silicon wafers and carbon nanotubes/nanofibers grown by catalytic plasma enhanced chemical vapor deposition (PECVD) were the two types of nanofilament arrays analyzed as cathodes materials. It was observed that the arrays of 5.8 μm height and 50 nm diameter carbon nanotubes exhibited geometrical enhancement factor of 240+-7.5%. The results show that carbon nanotubes/nanofibers arrays are best suited for nanofilament cathodes.

Growth of ultrahigh density single-walled carbon nanotube forests by improved catalyst design.

We have grown vertically aligned single-walled carbon nanotube forests with an area density of 1.5 × 10(13) cm(-2), the highest yet achieved, by reducing the average diameter of the nanotubes. We use a nanolaminate Fe-Al(2)O(3) catalyst design consisting of three layers of Al(2)O(3), Fe, and Al(2)O(3), in which the lower Al(2)O(3) layer is densified by an oxygen plasma treatment to increase its diffusion barrier properties, to allow a thinner catalyst layer to be used. This high nanotube density is desirable for using carbon nanotubes as interconnects in integrated circuits.