Analysis of anodic oxidation current of flattened p-type Si(111) surface in aqueous solution

The current-voltage curve of an atomically flattened hydrogen-terminated p-Si(111) surface is studied in 0.1 M ammonium borate solution in a potential region from the onset of the anodic current to about 3 V vs. Ag/AgCl. Three anodic current peaks are observed in this potential region. A deconvolution of the current-voltage (I-V) curve revealed that these three peaks are related to the oxidation of three Si monolayers from the surface. The current due to the oxidation of the first monolayer consists of two components with different peak potentials. Supported by Fourier transform infrared measurements, the component at the lower potential is attributed to the oxidation of Si-Si back bonds and the one at higher potential to the oxidation of Si-H bonds. The shape of the I-V curve is sensitive to the surface pretreatment, and we consider the shape to be a good indicator of the Si surface conditions. (C) 2003 The Electrochemical Society.