Screening effect and reliability are two of the most important issues in carbon nanotube-based field-emission devices. A thin Ti capping layer has been deposited on the hydrogen-pretreated catalytic iron nanoparticles to control the density of subsequently grown carbon nanotubes. In this way, the screening effect can be remarkably reduced due to the density of carbon nanotubes down to 107 from 109cm−2 as compared to the control specimens. Thus, the turn-on field can be improved to be 2.1 from 3.8V∕μm at the emission current density of 10μA∕cm2 . Furthermore, the electrical breakdown field can be increased to more than 7V∕μm and the lifetime of carbon nanotubes at high electric field (10V∕μm) can be greatly prolonged from a few seconds to more than 1h . This can be attributed to better adhesion and lower contact resistance between the carbon nanotubes and the substrate.

A multilayer catalyst, Co/Cr/Al, was employed to synthesize carbon nanotubes (CNTs) at atmospheric pressure by thermal chemical vapor deposition (thermal CVD). The relative growth rates, calculated on the basis of the average lengths of nanotubes grown at different temperatures, were utilized to estimate an activation energy of 0.84 eV for the multilayer catalyst. Such a low activation energy implies that the nucleation and growth of nanotubes could be effectively enhanced via the multilayer catalyst due to the well-distributed small catalytic nanoparticles by Al supporting layer and higher activity by Cr co-catalyst layer. It was also found that nanotubes grown using this configuration at 500 C exhibited excellent field emission characteristics, and showed a highly uniform emission image in a phosphor-coated anode plate.

Field-emission devices with a novel self-focusing gate structure using carbon nanotubes as emitters have been fabricated. Without additional focusing electrodes, the self-focusing gate structure employed a pair of gate electrodes parallel with the vicinity of emitters, which resulted in an asymmetric emission area as compared with the conventional gate structure. Therefore, electrons emitted from the emitters gave rise to an overlapping region on the anode plate so that a reduction of spot size had been achieved. According to the simulation results and luminescent images, this self-focusing gate structure had good control of the trajectory of electrons and therefore showed a smaller luminescent spot size than the conventional one. This gate structure, which utilizes a simple fabrication process, has the advantages of low-cost manufacturing and large-area scalability, and therefore is promising for application in field emission displays.

We undertake a theoretical study of an ideal lattice of c b l a r hard wall amidots in a low magnetic field where classical skipping orbits can exist" We study the transmission of electrons thmugh constrictions ktween antidots. and thence their paths through the lanice, which cm tahe the form of a correlated random walk. Analytic expressions for the conductivity tensor are derived, and mese give numerical values comparable with recent expenmenu.'

Uniformity has been considered to be one of the most important criteria for carbon nanotubes (CNTs) to be utilized as the emitters in field-emission displays (FEDs) or backlight units (BLUs). Using co-deposited Fe and Ti film as a catalyst, a uniform distribution of catalytic nanoparticles was obtained after hydrogen pretreatment as compared with nanoparticles obtained only using a pure Fe film. It might be attributed to the suppression of coalescence of the Fe nanoparticles in the codeposited Fe-Ti film during the CNTs growth. In addition, the length variation of the CNTs synthesized by thermal-chemical vapor deposition (thermal-CVD) was also remarkably suppressed. This resulted in a significant improvement of the luminescent uniformity, and homogeneous light emission was obtained from the CNTs at 700 V.