Time dependence of the electronic structure of an electron-beam-irradiated C60 film

Time dependence of the electronic structure of an electron-beam (EB) irradiated C60 film (20-30 nm thick) has been examined using in situ high-resolution ultraviolet photoelectron spectroscopy. It is found that the electronic states of the C60 film have been changed continuously from an insulator (pristine C60 films) to a semiconductor and finally to a metal as EB-irradiation time increased. This can be explained by the increase in polymerization degree of a C60 polymer with a given cross-linked structure derived from the general Stone-Wales rearrangement from [Beu et al.,Phys. Rev. B 72, 155416 (2005)]. In addition, this finding suggests that the electronic properties of the C60 film can be controlled only in the EB-irradiated region by varying the irradiation time, which is interesting when applied to electronic devices