Fe film (similar to 50 mn) have been deposited on psi substrate by electron beam evaporation technique. The bilayers have been irradiated by 100 MeV Fe7+ ions having fluences of 1 X 10(13), 1 X 10(14) and 5 x 10(14) ions cm(-2). SEM study of the unirradiated devices show surface modifications having a annular structures. From XRD study of the bilayer, it is observed that grain size has reduced from 70 to 25 nm after the irradiation for a fluences of 1 X 10(14) ions cm(-2). Moreover electronic transport data of the bilayer show practically no effect on the current flow for a fluence of 1 X 10(13) ions cm(-2) irradiation whereas for 1 x 10(14) ions cm(-2) fluence, there is very significant change in current flow (by two orders in magnitude) across the bilayer. However, for a higher fluence of irradiation 5 x 1014 ions cm(-2), the bilayer becomes highly resistive. It has been found from the above observations that the fluence of 1 X 10(14) ions cm(-2) of swift heavy ion irradiation is a optimum fluence. (c) 2007 Elsevier B.V. All fights reserved.