High-density horizontally aligned growth of carbon nanotubes with Co nanoparticles deposited by arc-discharge plasma method

High-density horizontally aligned single-walled carbon nanotubes are grown on a quartz substrate using Co nanoparticles deposited by arc-discharge plasma method. The Co nanoparticles with a density as high as 6.0x10(10) cm(-2) are formed by a single pulse of arc discharge at room temperature. The density of the aligned nanotubes is similar to 8 mu m(-1) in average. Multichannel nanotube field-effect transistors with a high-k top-gate structure are fabricated with aligned nanotubes. The devices show high-performance, normally on, and n-type conduction property without any doping process. A high on current of 1.3 mA and a large transconductance of 0.23 mS for a channel width of 100 mu m are obtained. The normally on and n-type property is attributed to fixed positive charges in the HfO(2) gate insulator and at the interfaces.