Nanotube field electron emission: principles, development, and applications

There is a growing trend to apply field emission (FE) electron sources in vacuum electronic devices due to their fast response, high efficiency and low energy consumption compared to thermionic emission ones. Carbon nanotubes (CNTs) have been regarded as a promising class of electron field emitters since the 1990s and have promoted the development of FE technology greatly because of their high electrical and thermal conductivity, chemical stability, high aspect ratio and small size. Recent studies have shown that FE from CNTs has the potential to replace conventional thermionic emission in many areas and that it exhibits advanced features in practical applications. Consequently, FE from nanotubes and applications thereof have attracted much attention. This paper provides a comprehensive review of both recent advances in CNT field emitters and issues related to applications of CNT based FE. FE theories and principles are introduced, and the early development of field emitters is related. CNT emitter types and their FE performance are discussed. The current situation for applications based on nanotube FE is reviewed. Although challenges remain, the tremendous progress made in CNT FE over the past ten years indicates the field's development potential.

High luminescent Li2CaSiO4:Eu2+ cyan phosphor film for wide color gamut field emission display

Li(2)CaSiO(4):Eu(2+) cyan phosphor screen for enlarging the color gamut of field emission display has been prepared and characterized. The luminance of Li(2)CaSiO(4):Eu(2+) phosphor film can reach as high as about 12000 cd/m(2) under the conditions of V(a) = 7 kV and J(a) = 2.8 mA/cm(2). The cathodoluminescent spectrum, luminance, saturation current density and degradation property are compared with another cyan phosphor Mg(2)SnO(4):Ti(4+),Mn(2+). It is found that Li(2)CaSiO(4):Eu(2+) phosphor exhibits narrower emission band, higher luminance, higher saturation current density, higher resistance to electron bombardment, higher thermal stability and conductivity as well as purer color. Thus, Li(2)CaSiO(4):Eu(2+) has great potential in application in field emission display as well as light emitting diode.

Highly efficient field emission from carbon nanotube-nanohorn hybrids prepared by chemical vapor deposition

Electrically conductive carbon nanotubes (CNTs) with high aspect ratios emit electrons at low electric fields, thus applications to large-area field emission (FE) devices with CNT cathodes are attractive to save energy consumption. However, the poor dispersion and easy bundling properties of CNTs in solvents have hindered this progress. We have solved these problems by growing single-walled CNTs (SWNTs) on single-walled carbon nanohorn (SWNH) aggregates that have spherical forms with ca. 100-nm diameters. In the obtained SWNT-SWNH hybrids (NTNHs), the SWNTs diameters were 1-1.7 nm and the bundle diameters became almost uniform, that is, less than 10 nm, since the SWNTs were separated by SWNH aggregates. We also confirmed that a large-area FE device with NTNH cathodes made by screen printing was highly and homogeneously bright, suggesting the success of the hybrid strategy.

Enhanced field emission properties of vertically aligned double-walled carbon nanotube arrays

Vertically aligned double-walled carbon nanotube (VA-DWCNT) arrays were synthesized by point-arc microwave plasma chemical vapor deposition on Cr/n-Si and SiO(2)/n-Si substrates. The outer tube diameters of VA-DWCNTs are in the range of 2.5-3.8 nm, and the average interlayer spacing is approximately 0.42 nm. The field emission properties of these VA-DWCNTs were studied. It was found that a VA-DWCNT array grown on a Cr/n-Si substrate had better field emission properties as compared with a VA-DWCNT array grown on a SiO(2)/n-Si substrate and randomly oriented DWCNTs, showing a turn-on field of about 0.85 V µm(-1) at the emission current density of 0.1 µA cm(-2) and a threshold field of 1.67 V µm(-1) at the emission current density of 1.0 mA cm(-2). The better field emission performance of the VA-DWCNT array was mainly attributed to the vertical alignment of DWCNTs on the Cr/n-Si substrate and the low contact resistance between CNTs and the Cr/n-Si substrate.