Kinetics of oxide growth and oxygen evolution on p-Si in neutral aqueous electrolytes

The growth of thin oxide films on wafers of p-Si, (100) orientation, was studied in neutral and acidic aqueous solutions up to 10 V by microelectrochemical (cyclic voltammograms and current transient of potential steps) and microellipsometric measurements. The oxidation occurs according to the high-field law with high-field parameters log(i ₀/A cm^–2)=–13.4±1 and β=10.6±0.1 nm V^–1. The oxide films represent an almost ideal dielectric material with ε=6.5. Oxide growth is not affected by oxygen evolution, which starts at potentials >3 V. The electron transfer process was analysed in relation to the oxygen evolution reaction. Owing to the presence of oxide thicknesses higher than 2 nm at this point, direct tunneling is less probable and a tunneling via traps should be assumed for the charge transfer. Evidence for coupled electronic and ionic conduction is presented. A contribution of the valence band in SiO₂ is stated for the corrosion of oxides at potentials >4.5 V. Electronic Publication