Chemistry Reference
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dynamically adsorbed by H and dissolved into the solution. The efficiency of hydro-
gen evolution and dissolution valence as a function of potential under various condi-
tions is summarized in Fig. 5.23.
Due to the formation of hydrogen bubbles the space within the pores may not be
fully filled by electrolyte. It has been found that for the PS formed on heavily doped
p
-type silicon in concentrated HF solution only slightly more than half of the pore
volume is filled by the electrolyte.
40
The rest is occupied by the hydrogen gas gener-
ated during PS formation. However, it has been suggested by Lehmann and Foll
763
that
the formation of hydrogen bubbles is likely to occur at the opening of the pores instead
