Characterization of porous silicon layers by grazing- incidence X-ray fluorescence and diffraction

Abstract

X-ray fluorescence and diffraction has been performed on porous silicon samples at incidences near the critical angle for total external reflection. By fitting the X-ray fluorescence intensity as a function of the incidence angle, density and density variarations versus depth have been obtained for porouslayers prepared under different conditions. Good agreement with other techniques has been obtained. Grazing-incidence diffraction measurements show broad diffuse scattering around Bragg reflections, which is related to the pore structure. Therefore, structure information concerning the mean pore size, correlations between pores positions, the local lattice distortions within the porous silicon in relation to the existence of pore, has been demonstrated. Informations obtained from single measurement from the Full-Width at Half Maximum and from the tails of the diffuse scattering are discussed.