Chemistry Reference
In-Depth Information
the reactions, particularly the coverage of oxide at the pore bottom, is changed, which
results in the change of morphology.
8
Mass transport of uncharged species in an electrolyte occurs by either convec-
tion or diffusion. Given the conditions for PS formation, convection inside pores
via physical stirring is only possible through the formation, growth, and movement of
hydrogen bubbles. It has been reported that the pores during their growth are not fully
filled with electrolyte, due most likely to the formation of hydrogen bubbles.
40
However,
it has been argued that hydrogen bubbles may not be formed in the mass transport
within pores because if they are formed inside pores they will block the pore and
significantly reduce the rate of mass transport.
12
In the potential range near the current peak before the electropolishing the current
is limited primarily by the diffusion of HF from the bulk to the silicon/electrolyte inter-
face.
33
In this region the coverage of PS on the electrode surface is no longer complete
because oxide formation and dissolution proceed on a significant part of the surface.
