X-ray diffraction and reflectivity studies of thin porous silicon layers

High resolution X-ray diffraction and reflectivity have been used for the structural characterization of thin porous silicon layers of p and p(+) doping type. Thin porous silicon layers studied either by diffraction or reflectivity, in the range of 10-1000 nm, exhibit several thickness fringes, corresponding to a lateral homogeneity of the layer thickness. The comparison between the experimental results with simulations enables one to deduce structural information relative to the porosity, thickness, lattice parameter as well as interface thickness. For p(+) type samples a double fringe system was observed, showing the existence of a surface film probably at the porous silicon layer top surface.