Mechanisms of Field Ionization and Field Evaporation on Semiconductor Surfaces

Abstract

This paper describes the mechanisms of field ionization (FI) and field evaporation (FE) on semiconductor surfaces. By including experimental results obtained up to the present, it is demonstrated that field penetration (FP) into the surface of these semiconductors has significant influence on these mechanisms. The best image field and the ion current generation for these materials are discussed on the basis of the FI theory in which FP is taken into account. The evaporation field, the ionization states of evaporated ions and preferential FE for these materials are also discussed on the basis of the FE theory in which FP is taken into account. Moreover, by obtaining the ion current-voltage characteristics of an FIM by means of image photometry, it has been made clear that the ion current at the best image field for these materials depends not on the gas supply, but principally on the ionization probability of the imaging gas.