Oxide growth characteristics on Al (100), (110), and (111) surfaces: A chemo-mechanical evaluation

The oxide growth mechanism on Al (100), (110) and (111) and the corresponding oxide film properties were examined using all-atom molecular dynamics simulations. The growth kinetics of the aluminum oxide film at a constant dose rate of oxygen were analyzed. Al (110), with a structurally unstable surface and a high surface energy, showed the highest oxide growth rate, oxygen adsorption rate, and adsorption energy. However, as the crystallinity of the surface structure collapsed as oxidation progressed, the reaction energy of Al (110) with atomic oxygen converged to the same value as that of Al (100) and (111). Instead, a high anisotropic residual stress remained in the oxide layer on Al (110) with the aid of high surface energy and anisotropic surface structure. The results suggest that although the chemical bonding features of the as-prepared oxide layers were similar, the intermediate process of oxide film formation and the resultant mechanical properties were highly dependent on surface crystallinity. The oxidation kinetics model presented in this work showed consistency with other reported ab initio calculations. Moreover, it also successfully reproduced the experimental fact that the formation speed of oxygen islands on Al (100) is more delayed than that on Al (111).

Automated summary

Aluminum oxide growth mechanism and film properties were examined on Al (100), (110) and (111) surfaces using molecular dynamics simulations. While Al (110) showed the highest growth rate and oxygen adsorption rate due to its unstable surface and high surface energy, the reaction energy eventually converged with Al (100) and (111) as oxidation progressed. The high anisotropic residual stress in the oxide layer on Al (110) was attributed to its high surface energy and anisotropic surface structure.