Chemistry Reference
In-Depth Information
concentration. On the
n-
electrode at more negative potentials than the plateau region,
current sharply increases due to hydrogen evolution. Under illumination, the quantum
efficiency of the
p-
Si
Si
is about 2 due to the injection of holes from the
which is
different from that at high ratios.
An anodic plateau current is measured on
n
-Si in the dark thus indicating elec-
tron injection into the conduction band. This plateau current is only slightly affected
concentration. Illumination of the
by HF concentration but is proportional to
-Si
causes an increase of the anodic plateau current with a quantum efficiency of about 2.8
due to electron injection into the conduction band by the silicon dissolution inter-
mediates. The quantum efficiency for the anodic photocurrent depends on the
ratio, about 2.8 at a high
n
ratio (>20) and about 1 at very low ratios.
195,196
in HF
solution on silicon electrodes depends on the ratio of from 0.5 to 1000. At
high ratios (>20) the reduction proceeds on the bare silicon surface whereas
at low ratios (<10) the reduction is inhibited by the formation of a chromium complex
containing trivalent and hexavalent entities
According to Meerakker and Vegchel,
the reduction kinetics of
can decompose under the effect of HF, resulting in hole injec-
tion which is responsible for the high quantum efficiency of the cathodic photocurrent
on
p-
Si.
