Structural stability of irradiated metallic and non-metallic films

Abstract

The segregation charge transfer model allows the interpretation of the nucleation of either crystalline or vitreous phases in binary non-metallic as well as metallic compounds, ion bombarded under conditions favourable to the formation of dense collision cascades. At the cascade–matrix interface a non-equilibrium electronic density profile forms and it is re-equilibrated by charge transfer reactions (CTRs), each involving a couple of dissimilar atoms, which undergo single ionization. The energy cost associated with a single CTR and the local volume change provoked by CTR products are evaluated. Thresholds in the values taken by the above physical quantities are found for both families of irradiated materials. Those thresholds separate the compounds amorphized from those remaining crystalline under ion bombardment.