Angle-Resolved Field Emission of Individual Carbon Nanotubes

Individual multiwalled carbon nanotube (CNT) emitters were fabricated on a Si substrate by electron-beam lithography. The CNT emitter had seven anodes with orientation theta ranging from 0-60 degrees with respect to the CNT axis. Field-emission experiments revealed that the emission current l was largest along the theta = 0 degrees direction and decreased monotonically with increasing theta; at theta = 56 degrees l decreased to one-thirtieth of its value at 0 degrees. The emission surface area also decreased by four orders of magnitude as theta increased from 0 to 56 degrees. In contrast, the field enhancement factor increased by a factor of five in the same angular range. It was found that 80% of the emission current was contained within 20, from the CNT axis. The results indicate that a CNT emits electrons most effectively along its CNT axis. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.07240