Structural stability of irradiated metallic and non-metallic films

The segregation charge transfer model allows the interpretation of the nucl eation of either crystalline or vitreous phases in binary non-metallic as w ell as metallic compounds, ion bombarded under conditions favourable to the formation of dense collision cascades. At the cascade-matrix interface a n on-equilibrium electronic density profile forms and it is re-equilibrated b y charge transfer reactions (CTRs), each involving a couple of dissimilar a toms, which undergo single ionization. The energy cost associated with a si ngle 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 c ompounds amorphized from those remaining crystalline under ion bombardment. (C) 2000 Published by Elsevier Science S.A. All rights reserved.