Mechanochemical oxidation of silicon and selectivity of oxide superficial layer dissolution in aqueous solutions of HF and KOH

Mechanochemical oxidation of silicon and selectivity of oxide layer dissolution in diluted solutions of HF and KOH were investigated. Energy-intensive grinding of Si is accompanied by changes in state and composition of superficial layers and by significant decrease in crystallinity. The effect of the polarity of liquid grinding environment on the amorphisation is not significant. The permittivity of liquid influences oxidation of silicon and surface concentration of damage centers. The porous oxide shell covering the ground particles controls the adsorption behaviour of Si and consequently its dissolution in diluted solutions of HF and KOH. Stimulating or inhibiting effect of mechanically induced pre-oxidation depends upon the mechanism of dissolution. While selective dissolution of oxide in HF is facilitated by the pre-oxidation, the direct dissolution of silicon in alkaline solvents is inhibited by oxide surface layer.