Passive film coalescence

According to the point defect model (Lin et al., 1981 Chao et al., 1981), the adsorption and incorporation of Cl" at the oxide surface is accompanied by the formation of cationic vacancies which diffuse to the metal-oxide interface where they can coalesce, which would cause breakdown of the passive film. 

Si-Si bonds on the crystalline substrate surface also break to aid in the accommodation of strain in the clusters of deposited material, resulting in partial loss of the surface structural order. Tlie coordination defects of the Si atoms in the partially amorphized surface are passivated by transport of available H atoms that are bonded to overcoordinated Si atoms in the deposited clusters. These processes determine the structure and composition of the interface that forms between the deposited material and the crystalline substrate. The above relaxation mechanisms stabilize the amorphous pockets on the deposition surface, which grow and coalesce as more radicals arrive from the gas phase to form an amorphous film on the crystalline substrate. 

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