Inelastic processes in low-energy ion-surface collisions

Studies involving ion-solid interactions in the range of a few eV to a few keV that are intermediate between thermal gas-surface interactions and high energy bulk implantation are collectively examined in this review. The interactive process is traced in a phenomenological manner by providing a simple treatment of the different physical and chemical phenomena involved. The kinematics of noble gas ion as well as atomic and molecular reactive ion interactions with surfaces are treated in terms of classical dynamics and experiments are described that probe the nature of ion-solid interaction potentials by examining the scattering of ions from surfaces and the charge exchange processes operative during scattering. Molecular ion scattering is investigated and the behavior interpreted in terms of partial dissociation that results in both atomic and molecular scattering. A neutralization model is described that considers the interaction domain to be divided into three steps: the incoming trajectory, the close encounter, and the outgoing trajectory. A spectrum of possible results from the interaction process is described; these include reaction and chemical alteration of the target surface, desorption of adsorbate atoms by hyperthermal physical/chemical interaction, and accumulation of a high surface concentration of the projectile species, viz. film deposition. These studies investigate the science basic to a number of technological phenomena and represent an elegant approach to the simulation of a number of these phenomena in the controlled environment of ultra-high vacuum. Qualitative and quantitative arguments are made for a number of the experimental results and cross-examination of data from different laboratories is made in terms of simple kinetic and thermodynamic concepts to illustrate fundamental similarities in the various studies.