Effect of swift (∼100 MeV) heavy ion irradiation on surface morphology and electronic transport in Fe film on Si substrate

Fe film (∼50 nm) 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 × 1013, 1 × 1014 and 5 × 1014 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 fluence of 1 × 1014 ions cm−2. Moreover electronic transport data of the bilayer show practically no effect on the current flow for a fluence of 1 × 1013 ions cm−2 irradiation whereas for 1 × 1014 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 × 1014 ions cm−2, the bilayer becomes highly resistive. It has been found from the above observations that the fluence of 1 × 1014 ions cm−2 of swift heavy ion irradiation is a optimum fluence.