X-RAY-DIFFRACTION STUDY OF THIN POROUS SILICON LAYERS

High resolution X-ray diffraction measurements are performed on porous silicon samples (p(+) type, 40% porosity) of various thicknesses (fro m 0.03 to 20 mu m). In the thicker samples narrow Bragg peaks are obse rved for as-formed samples, with profiles close to those of dynamical diffraction theory. For thin samples (in the 0.1 mu m range) the Bragg peak of the porous layer is not resolved, but appears as a shoulder o n the substrate peak. Thickness fringes are observed, from which simul ations give information on these thin PS layers, showing that the poro us layer surfaces are well defined.