Introduction

Abstract

This book discusses the interaction of energetic particles with solids. The particles may be neutral atoms or ions, which may hit a solid from outside or may start inside the solid. Particles arriving from outside the solid are usually termed projectiles. The adjective “energetic” indicates that the particle energy ranges from the eV to the MeV region. If a projectile penetrates a solid target it will be scattered due to collisions with target atoms, which lead to an elastic energy loss and to a change in direction. In addition, the projectiles suffer an inelastic energy loss due to collisions with electrons. Finally, when the projectiles have lost all their energy, they are deposited somewhere in the target. Other possibilities are that the projectiles are backscattered after some collisions or that they are transmitted, if the target is thin enough. The processes mentioned are well known under the names implantation, ranges, backscattering or reflection, and transmission. So far the projectiles have been discussed, but that is only one part of the process. The elastic energy lost by a projectile in a collision is transferred to a target or recoil atom, which itself collides with other target atoms and so forth. In this way the projectile creates what is called a cascade. Target atoms may acquire a kinetic energy large enough to escape from the solid, a process called sputtering. If the target atom is removed from the surface where the projectile hits the solid, the process is named backward sputtering, to distinguish it from transmission sputtering, where the target atom is removed from the other side of a thin foil.