Formation of nanoscale metallic structures on cupric nitride thin film surface by the impact of 200 MeV Au15+ ions

Cupric nitride films deposited on borosilicate glass and Si substrates by RF reactive sputtering are irradiated by 200 MeV Au15+ ions from Pelletron accelerator. On-line elastic recoil detection analysis (ERDA) technique shows a large depletion of N (∼75% depletion) from the films due to electronic sputtering effect of heavy ion whereas the copper content remains unchanged. This observation is associated with a sharp rise in sample ladder current signifying an enhancement of electron emission from the film during irradiation. The surface of the as deposited film studied by atomic force microscope (AFM) shows nanodimensional grain formation. Conducting AFM (CAFM) measurements show that at certain regions (10–30 nm) of the irradiated film surface a rapid rise of current (∼9000 pA) takes place. Enhancement of electron emission together with conducting AFM measurements lead us to conclude that conductivity of the surface enhances due to formation of nanodimensional metallic zones under Au ion impact. The entire process is understood on the basis of thermal spike model of ion–solid interaction.