Rinsing and drying studies of porous silicon by high resolution X-ray diffraction

The remarkable single-crystal property of p+-type porous silicon (PS) is used to investigate, with high resolution X-ray diffraction, the effects of silicon crystal transfer from wet to dry state: these effects are emphasized by the porous silicon’s large specific area. The transfer of silicon from a hydrofluoric acid solution to air via a rinsing stage in water is of fundamental and technological interests as it occurs in most of chemical treatments of silicon. First, during drying, a contraction of the PS layer is observed, related to the change of surface chemistry, in addition with some reversible deformation. Second, the rinsing stage in water leads to different behavior depending on the rinsing duration: short rinsing stage reduces the strong elongation observed on unrinsed PS while long rinsing stage leads to non-homogeneous strains in the PS layer.