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.

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.

We found out the promising catalyst materials(NiPd). The NiPd not only has the low melting point but also has the Pd enhancing the surface diffusion at low temperatures(<500'c ). With the Pd film thickness increasing, we could control the CNT density and synthesize more aligned and uniform CNTs. We also obtained the better electrical properties including lower turn-on field (3.4 V/um) and higher current density (34.3 mA/cm2) for NiPd as catalyst. For the advantages described above, we believe that the difficulty of low temperature on FED can be overcome. Further, the large area field emission display might be fabricated in the future.