Nanoscratch testing of C-60 thin films irradiated with N ions

Nanoscratch tests were performed in 170 nm thick C-60 films using a depth s ensing nanoindenter system with a lateral force measuring attachment. The f ilms were irradiated with N+ ions at 170 keV and fluences ranging from 5 x 10(11) to 5 x 10(15) N/cm(2). The scratches were 400 mum long and the used loads varied from 100 to 2500 muN. The measured friction coefficient change s from 0.23 for the C-60 pristine film to 0.09 for the irradiated film with the highest fluence. The decrease in the friction coefficient with fluence is correlated with ion irradiation damage, total transferred energy densit y by the ions to the film and with film hardness. (C) 2001 Elsevier Science B.V. All rights reserved.