Cathodic Behavior and Redox Couples - Electrochemistry of Silicon and Its Oxide - page 251

n -Si whereas the growth rate is higher on p- Si This is attributed to the higher surface

electron concentration on n- which is required for reduction and to the higher

hole concentration on p -Si surface required for silicon dissolution. Figure 6.15 shows
the effect of illumination on the size and density of precipitates. Illumination results in
a large increase in density of precipitates. For

Si

p -Si illumination increases surface elec-

-Si it increases the driving force measured by the differ-
ence in the Fermi level of the electrons and the redox potential of the copper in the
solution. 253,407 Also, during electroless deposition, dissolution of silicon substrate leads
to the formation of pits. 237,293 For n -type samples, metal deposition and silicon dissolu-
tion occur locally with nuclei growing in the bottom of etched pits toward the surface.

tron concentration and for n

In contrast, for samples the deposition occurs on the surface. Deposition of nickel
found to be more uniform on the patterned surface due to the
hydrophilic nature of the oxide. It has been reported that deposition of Pt in 0.5 M
at pH 2.9 at certain potentials results in the formation of nanoholes 20-80 nm
1044

p

microdots is

wide and 0.6-0.7 nm deep.

6.4. DEPOSITION OF SILICON

Silicon can be deposited at large cathodic potentials in solutions of
and other silicon-containing compounds in organic solutions. 363,419 The
i-V curves show a passivationlike current peak and a much smaller current in the
reverse scan. Smooth films up to thick can be deposited but a thicker film tend
to develop cracks. Also, the film contains F, C, O, and N as impurities and can be doped