Introduction

Ion beam processing of materials results from the introduction of atoms into the surface layer of a solid substrate by bombardment of the solid with ions in the electron-volt to mega-electron-volt energy range. The solid-state aspects are particularly broad because of the range of physical properties that are sensitive to the presence of a trace amount of foreign atoms. Mechanical, electrical, optical, magnetic, and super-conducting properties are all affected and, indeed, may even be dominated by the presence of such foreign atoms. The use of energeticions affords the possibility of introducing a wide range of atomic species, independent of thermodynamic factors, thus making it possible to obtain impurity concentrations and distributions of particular interest; in many cases, these distributions would not be otherwise attainable.

Recent interest in ion beam processing has focused on the studies of ion implantation, ion beam mixing, ion induced phase transformations, and ion beam deposition. These interests have been stimulated by the possibilities of synthesizing novel materials with potential applications in the semiconductor, tribological, corrosion, and optical fields.

Ion beam processing provides an alternative and non-equilibrium method of introducing dopant atoms into the lattice. In typical applications, a beam of dopant ions is accelerated through a potential of 10–100 kV. The implantation system shown in Fig. 1.1 illustrates the basic elements required in this technique: ion source, acceleration column, mass separator, and target chamber.