||2009||||||||||Jung-Hyun Cho, Sun-Taek Lim and Gon-Ho Kim||Korea||  Transparent conducting films (TCFs) have various electronic applications such as flexible display, touch panel, solar cells, electromagnetic wave shielding, and so on. Bundle type single-walled carbon nanotube (SWNT bundle) network is a promising substitute material for pre-existent indium tin oxide (ITO) film because it has better mechanical properties and lower cost for fabrication. However, electrical conductivity of SWNT bundle network is lower than that of ITO because of loose contact among the bundles. In this study, energetic particle irradiation method was introduced to improve the conductivity from the viewpoint of irradiation-induced cross-welding among the bundles. To investigate effect of particle irradiation on electrical conductivity of the SWNT bundle network, particle irradiation experiments were carried out with transparent film made of the bundle by filtration and spray-coating. The irradiated particles were Ar ions with energy of 20, 90 eV and 7.5 keV accelerated in plasma sheath device with DC biased and pulsed target. Also the 10 MeV proton irradiation using cyclotron accelerator in Korea Institute of Radiological and Medical Sciences was adopted. Defect on SWNT bundle by 20 and 90 eV Ar ion irradiation and amorphization of the bundle by 7.5 keV Ar ion irradiation were observed. Because of these damages, the conductivity of the bundle network was reduced. For 7.5 keV Ar ion irradiation, the conductivity was reduced with increase of ion dose. However, after 10 MeV proton irradiation, the conductivity of SWNT bundle network was improved by formation of cross-welding among the bundles without severe damages. The conductivity increased with proton dose. More details and analysis on correlation between conductivity and deformation of SWNT bundles with consideration of particle energy loss in the bundle will be presented.