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In-Depth Information
decay because the rate of formation of oxide film becomes faster than the rate of its
dissolution.
The current multiplication due to the presence of fluoride depends on the pH of
the solution, as shown in Fig. 5.11.
873
It decreases with increasing pH and almost dis-
appears above pH 7. At high pH, formation of oxide prevents direct reaction of silicon
with fluoride species, and the pH value at which this occurs decreases with increasing
light intensity.
5.3.1 Quantum Yield and Surface Recombination
The photocurrent quantum efficiency,
Y
, of
n
-Si electrode in fluoride solutions
depends on current as shown in Fig. 5.12.
73
It is high at low current densities and
decreases with increasing current densities to a plateau value of about 2; Fig. 5.12 shows
