Thin layers and multilayers of porous silicon: X-ray diffraction investigation

Porous silicon is a unique example of a porous material exhibiting the properties of a nearly perfect single crystal. High resolution x-ray diffraction has been used to investigate thin p− and p+ type porous silicon layers in the 100–1000-nm-thickness range. Since several thickness fringes are observed, the comparison between experimental results and simulations enables one to deduce information about the main structural parameters such as porosity, lattice parameter, thickness, and heterotransition width. Porous silicon multilayers have also been investigated: some satellites are clearly observed. The obtained results are then compared and discussed with the literature.