Determination of coverage in passivated porous silicon by Brillouin spectroscopy

Abstract

Brillouin scattering has been performed to probe surface acoustic waves in porous silicon films that have been chemically modified with various surface passivators. The surface Rayleigh mode and two film acoustic modes are observed. Unlike the Rayleigh mode, the two film modes are found to exhibit velocity dispersion. The effect of passivation is manifested as a shift of Brillouin peaks to lower frequencies relative to those of the freshly prepared porous silicon samples. The coverage of the surface area of the pores of the entire porous layers by the respective chemical passivators has been estimated from the phase velocity of one of the film modes. © 2001 American Institute of Physics.