Interface width of anodic native oxide - InSb structures

Using our improved quantitative analysis of Auger electron spectroscopy (AES) depth profiles, we have found a linear relationship between the interface width of plasma- and wet-anodized InSb (111) and the oxide thickness in the range of 15-180 nm. Using a simple etching technique we have been able to ascertain that the effect was inherent to the oxidation process and not a result of the sputtering process. We have developed a theoretical model that explains the linear relationship in terms of field-enhanced diffusion and oxidation reaction. The model is based on our earlier experiments that demonstrated the oxygen diffusion through the oxide to the interface. Application of the model to the results of over 30 different AES depth profiles yields excellent agreement with the experimental observations that show that the interface width is about 0.25 of the total oxide thickness. The results support the thermodynamic model of anodization, indicating that interface formation is the last step of the oxide growth process.