Electronic and surface properties during the etch-back of anodic oxides on Si(111) surfaces in 40% NH4F solution

An etch-back procedure of anodically oxidized Si(111) surfaces was investigated by photoluminescence, photo voltage, atomic force microscopy and infrared spectroscopic ellipsometry. The first step was the preparation of an H-terminated Si surface in diluted HF solution. The second step was the formation of an anodic oxide layer at different potentials in 40% NH4F solution followed by oxide etching in the same solution leading to an H-passivated Si surface. The different experimental results are discussed with respect to oxide thickness, surface roughness, interface defect concentration and surface charging.