Detailed analysis of the silicon surface under low-energy oxygen bombardment at atomic resolution

A detailed analysis of the amorphous-SiO2/crystalline-Si(011) interface formed by low-energy oxygen bombardment is performed by high-resolution Rutherford backscattering spectroscopy and spherical aberration-corrected scanning transmission electron microscopy (STEM). The atomic level analyses indicated a few nanometers of displaced Si atoms layer immediately below the synthetic SiO2 layer. A comparison between intensities of the high-angle annular dark field (HAADF) STEM image and the simultaneously acquired high-angle bright-field (HABF) STEM image shows that both intensities decreased at the existing layer of displaced Si atoms, and the relationship between these intensities cannot be explained by conventional image formation mechanisms. From detailed investigations using STEM imaging simulations, the HAADF STEM and HABF STEM images, which were simulated based on a realistic model, revealed the random distribution of a crystalline material and amorphous material at the interface; and this result agrees well with experimental results.