Recombination and local equilibrium in growing oxide films

Abstract

The possibility of a recombination of certain diffusing point defects in growing oxide films is examined within the framework of a simple collision model. Local equilibrium between diffusing cation interstitials and cation vacancies (or between diffusing anion interstitials and anion vacancies, or between electrons and electron holes) can represent a viable approximation for 100 Å oxide films when the average diffusing point defect density exceeds 1021/cm3; for a 100 μ thick oxide layer, the minimum defect density for such reduces to 1017/cm3. On the other hand, arguments are presented on the basis of physical considerations which indicate that local equilibrium between the diffusing cation and anion point defect species within the growing oxide film is not to be expected; likewise, local equilibrium between the diffusing electronic and ionic species giving rise to new oxide growth is not to be expected.