The effect of surfactant on the polarization behavior during porous silicon formation has been studied for p- and p(+)-type silicon wafers. The presence of surfactant showed strong effects on p-type silicon, whereas the pi-type silicon polarization curve changed negligibly with a surfactant. The anionic surfactant increased the overpotential; it was decreased by the cationic surfactant. The space charge layer mainly determines the dissolution process, since p-type silicon, which has a smaller capacity, was more affected than p(+)-type silicon. This is also supported by the capacity measurements of a p-type silicon: a more positive flatband potential in the anionic surfactant solution and a less positive flatband potential in the cationic one. The surface properties of p-type porous silicon have also been investigated by infrared spectroscopy. The absorption bands change in shape and in intensity, depending upon the surfactant. In particular, the cationic surfactant reduced the absorbance. The decrease is due to the chemical dissolution of the porous silicon layer. We can also see a correlation between the integrated absorbance and the electrode potential. (C) 2001 Elsevier Science Ltd. All rights reserved.