Ionization-assisted evaporative processes: techniques and film properties

The basic mechanisms of ion-surface interaction relevant to film growth are discussed; the methods of ionization-assisted evaporation processes are outlined; and the properties of deposited metal and compound films are discussed. The ultimate objective in thin-film deposition is the growth of thin films with predictable, stable, and reproducible properties equal to or better than those of bulk materials and, in addition, the synthesis of new materials. It is pointed out that ionization-assisted processes provide the means to achieve this objective, with the technique selected depending entirely on the application for which the film is required. The processes are many and varied but have a common element in that a principal aim is to achieve maximum ionization of the depositing atoms/molecules and/or the reacting gas species. The techniques have varying degrees of ionization efficiency and deposition rates, but all offer many advantages over conventional evaporative processes through the ion/surface interaction mechanisms. It is concluded that future developments will see better theoretical understanding of the relationship of the process parameters to film properties, the development of advanced ion-assisted deposition technology, and they synthesis of new materials