STUDIES OF COHERENT AND DIFFUSE-X-RAY SCATTERING BY POROUS SILICON

The microstructure of porous silicon layers has been studied by means of x-ray diffraction. Using a double-crystal diffractometer, the observed diffraction patterns give directly the mismatch between the lattice parameters of the porous layers and of the substrate, and the curvature of various porous silicon samples obtained in different conditions. From measurements with the same experimental set-up, but with a larger scan range, broad diffuse bumps produced by the pore structure have been observed. This new feature allows us to obtain structural informations on the porous silicon in a nondestructive way. In particular, we have observed the anisotropic pattern showing a preferential elongation of the pores perpendicular to the (100) surface.