Large field emission current density from well-aligned carbon nanotube field emitter arrays

Abstract

We have grown well-aligned carbon nanotube arrays by thermal chemical vapor deposition at temperatures below 800 degrees C on Fe nanoparticles deposited by a pulsed laser on a porous Si substrate. Porous Si substrates were prepared by the electrochemical etching of p-Si (100) wafers with resistivities of 3-6 Omega cm. These well-aligned carbon nanotube field emitter arrays are suitable for electron emission applications such as cold-cathode flat panel displays and vacuum microelectronic devices like microwave power amplifier tubes. Field emission characterization has been performed on the CNT-cathode diode device at room temperature and in a vacuum chamber below 10(-6) Torr. The anode is maintained at a distance of 60 mu m from the carbon nanotube cathode arrays through an insulating spacer of polyvinyl film. The measured field emitting area is 4.0 x 10(-5) cm(2). Our carbon nanotube field emitter arrays emit 1 mA/cm(2) at an electric field of 2 V/mu m; they emit a large current density as high as 80 mA/cm(2) at 3 V/mu m, which is orders of magnitude higher than any other results reported so far. The open tip structure of our carbon nanotubes and their good adhesion through Fe nanoparticles to the Si substrate are part of the reason why we can attain a large field emission current density within a low field. The field emitter arrays in our diode device are vertically well-aligned carbon nanotubes on the Si-wafer substrate. (c) 2001 Elsevier Science B.V. All rights reserved.