High current density field emission from arrays of carbon nanotubes and diamond-clad Si tips

Abstract

Collective emission degradation behavior of carbon nanotube thin-film electron emittersArrays of carbon nanotubes ͑CNT͒ and diamond-clad Si tips were grown by microwave plasma-enhanced chemical vapor deposition. The former ones were grown directly on prepatterned cobalt-coated silicon substrate, while the latter ones were grown on Si-tip arrays. Each array contains 50ϫ50 emitting cells and each individual cell is 3 m square. A maximum effective emission current density of about 17 A/cm 2 ͑at a macroscopic field of 17.5 V/m͒ has been demonstrated, while a macroscopic emission current density of 10 mA/cm 2 with operating fields around 10 V/m can be routinely achieved from an array of CNT emitters. In contrast, operating fields above 20 V/m were needed to draw a comparable emission current density from all of the diamond-clad Si tips arrays. Emission stability test performed at 40 mA/cm 2 for CNT arrays also showed little sign of degradation. Due to the high efficiency of electron emission, simple sample process, and large area growth capability, field emitter arrays based on CNT are attractive for flat panel display applications.

Electronic structure of the carbon nanotube tips studied by x-ray-absorption spectroscopy and scanning photoelectron microscopy

“…Details of the preparation of these CNTs can be found elsewhere. 15 Figure 2 shows the angle-dependent C K-edge XANES spectra of the aligned CNTs. The spectra were normalized using the incident beam intensity, I 0 , and keeping the area under the spectra in the energy range between 345 and 360 eV ͑not fully shown in the figure͒ fixed.…”

Field Emission Characteristics of Amorphous Diamond

“…Carbon-based materials, such as diamond films, DLC coatings, and carbon nanotubes (CNTs) are particularly attractive for these applications. [5][6][7][8][9][10] However, the emission mechanisms for these materials are not wellunderstood, although a number of hypotheses have been proposed. In the past, the negative electron affinity (NEA) of a diamond surface was believed to play an important role in expelling electrons out of diamond or diamond-like carbon.…”

Band-gap dependence of field emission from one-dimensional nanostructures grown onn-type andp-type silicon substrates

“…The microgeometry of these nanostructures demonstrated how some of the parameters of the Fowler-Nordheim equation, 2 especially the field enhancement factor, used to describe field emission in metals, could be tailored to achieve lower threshold voltages for electron emission. The material, 3 its microstructure, 4 the microgeometry ͑that is, whether the emitter is a tip, tube or rod͒, 5,6 any adsorbed species and surface modifications, 7,8 and electrical and other physical properties of the emitting material were thoroughly studied to give us an insight into this phenomenon of field emission. However, these nanostructures are often supported on attractive substrates such as silicon, for future integration to the device technology, whose role in determining the emission efficiency has been unclear.…”