Chemistry Reference
In-Depth Information
formed.
10,12,16
The pore diameter of this micro PS layer is less than 2nm and the thick-
ness of this layer changes with illumination intensity and the amount of charge passed.
16
Also, the diameter of macropores on front-illuminated
-Si changes with the amount
of charge passed.
763
The pore size and depth variation of PS on
n
-Si are very different
for front- and back-illuminated samples. The diameter of pores on two-layer PS will
be further discussed in Section 8.3.6.
For very deep pores the diameter may start to increase with a decreased growth
rate due to the effect of the diffusion process in the pore electrolyte. The depth at which
this occurs depends on current density and HF concentration. Figure 8.27 shows that
the maximum depth of pores formed on back-illuminated
n-
Si without changing of
n
