Field Emission Properties of Individual Carbon Nanotubes in Nanorobotic Manipulation and Electron-Beam-Induced Deposition

摘要

Field emission properties of individual multi-walled carbon nanotubes (MWNTs) were studied in nanorobotic manipulation and electron-beam-induced deposition (EBID). Nanotube emitters are constructed by picking up and assembling individual nanotubes on a commercially available atomic force microscope (AFM) cantilever or a tungsten probe. The relationship between field emission current and interelectrode distance was obtained by changing the distance between the tip of the nanotube emitter and the counterpart anode, which can be potentially applied as the principle for an approaching sensor to detect nanometer scale distance by observing field emission current in real time. Field emission current on a microampere scale from a CNT emitter was shown to be strong enough for EBID without obviously degrading emitters. Deposit topology was related to current density or the emitter shape, suggesting that information on emitter geometry could be obtained from EBID deposits. Energy dispersive X-ray spec-trometry (EDS) analysis of deposits from W(CO)6 showed that the tungsten mass exceeds 80% on the average among compositions. Much higher voltage may degrade the emitter, and saturated current may be used to adjust the emitter length in a controlled way.