Carbon nanofibers; could be grown oil the smooth plane area on MgO substrate surface in the lateral direction to the substrate by the catalytic role of iridium. In the case of the rough surface area of the MgO substrate, the vertical growth of the carbon nanofibers was dominant. Laterally-grown carbon nanofibers formed a self-assembled interconnection network. The surface electrical resistivity of the self-assembled lateral carbon nanofibers network decreased with increasing substrate temperature. A scanning tunneling spectroscopy measurement revealed the hand gap existence between -1 and 1V, which confirmed the semiconductor characteristics of the self-assembled lateral carbon nanofibers network. (c) 2005 Elsevier B.V. All rights reserved.