Chemical composition and interface structure of silicon oxide grown by pure water anodization

This work aims at the investigation of chemical composition and interface structures of oxide prepared by pure water anodization using Auger electron spectroscopy (AES) and Infrared absorption spectroscopy (IRS) measurements. Results show that the growth of stoichiometric silicon dioxide film is possible with anodization as evidenced by the features of 1106 cm^-1 in infrared measurement. In addition, the IR absorbance and the peak locations decrease almost linearly as the oxide grows thicker. High contents of Si-H and Si-OH are found in anodic oxide. In AES study, we found that the slower the growth rate of the anodization, the stronger the Si-O bonds. This observation is ascribed to effect of stressing the oxide film in a high electric field for long duration. In annealing study, we found that the interface thickness and the binding energies of Si (LVV) and O (KLL), in the oxide film can be either increased or decreased, governed by the initial anodic oxides, by the thermal annealing. The oxygen atomic ratio in the bulk of the samples are in the range of 55 ≈ 65%. After annealing, the oxygen atoms at the interface will migrate to the bulk of the oxide and the atomic ratio of oxygen increases to a value of about 70%.