Real-time detection of ambient oxidation of steps and terraces on Si(111)-(1×1):H by scanning force microscopy

摘要

The initial stage of oxide formation on Si(111)-(1×1):H, a highly controversial problem, has been studied using scanning force microscopy under ambient conditions (25% relative humidity at 20℃). Real-time monitoring of changes in the root-mean-squared (rms) roughness of the broad terraces and step heights was performed at the same surface spots. The height of the bilayer steps increased by 0.2-0.3 nm with a maximum after about 22 h and decreased afterward due to further oxidation of the terrace on a longer time scale. This finding clearly suggests fast bilayer step oxidation, as opposed to terrace oxidation, contrary to previous reports.