Pore formation in p-type silicon in solutions containing different types of alcohol.

Macroporous structure of silicon can be obtained with anodization in hydrogen fluoride (HF) solution. The macropore formation in the presence of alcohol was studied. Macroporous layer formation in a low-concentration HF solution is stabilized with the increasing number of carbon in alcohol. The dissolution at the topmost part of the porous layer is observed though the behavior depends upon the type of alcohol. Meanwhile, the total mass loss of dissolved silicon is almost constant. Such dissolution at the top surface occurs only when the concentration of HF is low. Adding organic solvents to the HF solution also leads to the suppression of the pore wall dissolution. The type of alcohol and HF concentration in solution affect the formation of porous silicon.