IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Nanotubes: Science and Applications Topical Conference Thursday Sessions
       Session NT+EL+NS-ThM

Paper NT+EL+NS-ThM10
In-situ Observed Atomic Structures at Carbon Nanotube Tips under Applied Electric Field

Thursday, November 1, 2001, 11:20 am, Room 133

Session: Nanotubes: Growth, Functionalization, and Sensors
Presenter: T. Kuzumaki, The University of Tokyo, Japan
Authors: T. Kuzumaki, The University of Tokyo, Japan
Y. Horiike, The University of Tokyo, Japan
T. Kizuka, Nagoya University, Japan
T. kona, Waseda University, Japan
C. Oshima, Waseda University, Japan
Correspondent: Click to Email
Carbon nanotubes show characteristics that are of particular interest as electron sources for field emission displays. In this study, tip structures of the nanotubes were in-situ observed under applied electric field by using a high-resolution transmission electron microscopy (HRTEM), field ion microscopy (FIM) and also field emission microscopy (FEM). HRTEM used in this experiment equipped with newly designed two specimen holders system. HRTEM observation successfully revealed that the tip of the nanotube bent during the field emission and protrudent structure was formed along the normal to the electric field. The results demonstrate that the electric field exerted mechanical stress on the surface structure. The in-situ observations lead us to development of nano-processing technology of the nanotubes. We found that burst and evaporation, and bonding of individual nanotube tips can be performed by the contact with another nanotube, amorphous carbon, or metals at the applied voltage. The tip of the nanotube was burst and evaporated at the contact at the applied voltage of more than 2V. At the burst tip, each carbon layer was often connected with the neighbor layers. After the tip burst, however, two nanotubes were bonded at the contact when the applied voltage was less than 2V. A rod specimen in which the nanotubes are sticking out of the tip was fixed on the tungsten wire with carbon binder, and was introduced into the ultra-high vacuum chamber of 3X10@super-8@ Pa for FIM and FEM experiments. Prior to the FEM observation, we evaluated the cap structure of the nanotubes by FIM and confirmed that several bright areas as emission sites, and they were either deformed honeycomb structures composed of hexagonal or pentagonal carbon rings. The bright area sites of the honeycomb structures observed in FIM moved with increment of the applied voltage.