Chemistry Reference
In-Depth Information
solutions the rate of the dissolution reaction is high and does not increase with poten-
tial because carriers are not involved. Due to the high concentration of the rate
of reaction is high in KOH solutions, but the rate is very low in HF solutions because
of the extremely low concentration.
According to reactions
and the concentration of hydrogen ions in both
solutions does not play a direct role in the reaction processes. This is because the con-
centration of adsorbed hydrogen which is generated when the silicon back bond
is broken, depends on [HF] in HF solutions or in KOH solutions independent of
the hydrogen ion concentration in the solution This explains why high dissolu-
tion rates are observed in KOH solutions, in which the concentration of hydrogen ions
is extremely low. It needs to note that in non-aqueous fluoride containing solutions with
salts such as the silicon surface is not terminated by H.
1015,1011
The dissolution
process is completely electrochemical and does not involve the formation of oxide due
to the lack of HF and
in the solutions.
