Molecular-dynamics simulations of electronic sputtering

摘要: Following electronic or collisional excitation of a solid by fast ion, an energized cylindrical region is produced which can lead to sputtering. Here ejection from such studied via molecular-dynamics simulations using Lennard-Jones and Morse potentials. Over the full range excitations yield vs energy release per unit path length in solid, we call $dE/dx,$ shown scale with binding density material for all materials at $dE/dx.$ This allows simulation results be applied low-temperature, condensed-gas solids more refractory over broad The effect distribution energies initial energizing events, spatial events given $dE/dx$ are examined. Three regimes have been identified. When event greater than escape energy, sputtering linear low With increasing spikelike regime occurs again becomes nonlinear For fixed radius then saturates so that very high nearly In this size increases radial extent track determined removal radially pressure pulse transport depth surface. Therefore, clear nonlinearities observed knock-on yields heavy ions require consideration cascades. solids, nonlinearity suggests excited varies manner different predicted lattice stopping power.