We report on a measurement of craters in thin dielectric films formed by XeQ+ (26 Q 44) projectiles. Tunnel junction devices with ion-irradiated barriers were used to amplify the effect of charge-dependent cratering through the exponential dependence of tunneling conductance on barrier thickness. Electrical conductance of a crater c(Q) increased by four orders of magnitude (7:9 104 S to 6.1 S) as Q increased, corresponding to crater depths ranging from 2 °A to 11 A° . By employing a heated spike model, we determine that the total energy required to produce the craters spans from 8 keV to 25 keV over the investigated charge states. Considering energy from pre-equilibrium nuclear and electronic stopping as well as neutralization, we find that at least 27 2% of available projectile neutralization energy is deposited into the thin film during impact.
Citation: Physical Review Letters
Pub Type: Journals