Anodic dissolution fundamentals electrolytic solutions

There is no doubt that specific adsorption of anions and organic species occurs in a wide potential range as the experiments were carried out in 0.1 mol dm HCIO4 supporting electrolyte at low concentrations (10 -10 mol dm ) of the species studied. It was found that the adsorption of anions exerts some influence on the anodic dissolution rate however, this effect is very far from that observed in the case of thiourea. In the latter case, the rate of anodic dissolution was significantly influenced by the presence of thiourea, even at its very low concentration. This behavior was ascribed to the strong interaction of thiourea with the metal ions and the formation of complexes both on the metal surface and in the solution phase. The phenomena presented were considered as a result of the adsorption competition of the species studied with C104 ions. Three fundamental mechanisms were formulated for the active dissolution ... 

The results presented in the previous sections show that the anodic reactions on a silicon electrode may proceed via different paths depending on the conditions and that those in HF solutions and those in KOH solutions are rather different. They also show that the mechanistic models proposed for the reactions in HF and KOH solutions from the many studies in the literature are largely separated. However, in both HF and KOH solutions, the silicon/electrolyte interface is fundamentally similar differing only in the concentrations of hydroxyl and fluoride ions. Thus, a reaction scheme must be coherent with respect to the experimental observations in both FIF and KOH solutions. For comparison. Table 5.8 summarizes the characteristic features of the reactions occurring on silicon in FIF and KOH, in terms of nature of the reaction, rate, effective dissolution valence, photoeffect, and uniformity of the surface. 

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