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Recently,it is found during our experiment that porous silicon
layer grows preferentially on the (100) over (111) Si surface.
The process consists of two steps. First,hydrazine is used to
etch V-grooves on (100) Si wafer. Second,the (111) walls of
etched V-grooves are selectively anodized in HF/ethanol
solution to form PSL. The anodization step takes place at a
smaller bias voltage for (111) than (100). Under the same
conditions of electrolyte concentration,current density and the
duration for anodization,the frequency is higher for the
measured PL from (100) than (111). From the current-voltage
measurement,we conclude that the formation of PSL on (100)
occurs at higher energy. We are also able to induce a blueshift
in the PL of PSL by controlling the HF concentration at a lower
level from the results of the photothermal deflection
spectroscopy experiment.
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