Field Emission Characteristics of Well-Aligned Carbon Nanotubes Synthesized in Organic Liquids

摘要

We have characterized the field electron emission from well-aligned carbon nanotubes (CNTs) synthesized in methanol using cobalt (Co) as a catalyst on silicon (Si) substrates. In order to prepare CNTs aligned vertically to the substrate, the physicochemical state of the Co catalyst was controlled by annealing in air at a temperature of 900 ℃ as a thermal preoxidation prior to the liquid-phase growth. For the CNT growth, the Co-loaded Si substrate was heated by applying a direct current through the substrate in methanol. Vertically well-aligned CNTs of different crystallinities were synthesized at temperatures of 600 and 900 ℃. Field electron emission characteristics of the synthesized well-aligned CNTs were measured using diode-type electrodes in a high-vacuum chamber. A low-threshold electric field of approximately 0.9 V-μm~(-1) and a very stable emission were observed in the CNTs with high crystallinity grown at a temperature of 900 ℃.