Positron annihilation and infrared spectroscopy studies of porous silicon

Measurements of the angular correlation of annihilation radiation and infrared absorption spectra were conducted with porous silicon samples, containing capillary macropores with a diameter of about 1 μm. The set of data shows that a high proportion of Si-O bonds contribute to positron annihilation and IR absorption for porous silicon. Annihilation parameters and estimated values of the specific surface area point to the availability of a nanoporous system in the macroporous silicon. Most likely the macropore surface is covered by the nanoporous material to a thickness of 100-200 nm. The characteristic size of the nanopores is estimated at 1-2 nm. Si-O bonds are located at the nanopore surface and do not exceed one monolayer. (Abstract Copyright [2003], Wiley Periodicals, Inc.)