Field emission and structure of aligned carbon nanofibers deposited by ECR-CVD plasma method

Aligned carbon nanofibers and hollow carbon nanofibers were grown by MW ECR -CVD method using methane and argon mixture gas at a temperature of 550 deg reesC. The carbon nanofibers and the hollow carbon nanofibers were deposite d perpendicularly on Si substrates and on Si substrates coated with Ni cata lyst, respectively. From TEM analysis the diameter and length of the nanofi bers are approximately 60 nm and 15 mum, respectively. Raman spectra of the se aligned carbon nanofibers showed new bands of 1340 and 1612 cm(-1) of th e first-order Raman scattering and 2660, 2940 and 3220 cm(-1) of the second -order Raman scattering. The second-order Raman scattering bands were assig ned to two overtone and one combination bands on the basis of a similar ass ignment of micro-crystal graphite by Nemanich and Solin. By the measurement of XPS Cls band energies of 284.6 eV for the carbon nanofiber and 284.7 eV for the hollow carbon nanofiber indicate mainly sp(2) carbon component in the inclusion of a small amount (< 5%) of oxygen in a high binding energy r egion (similar to 288 eV). Field emission characteristics of the well-align ed carbon nanofibers and hollow carbon nanofibers were investigated and the current densities were 7.25 and 0.69 mA/cm(2) at 12.5 V/mum, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.