Structural properties of p+-type porous silicon layers versus the substrate orientation: an X-ray diffraction comparative study

The structural properties of (001)- and (111)-oriented p+-type porous silicon samples have been investigated using X-ray techniques. X-ray reflectivity applied to thin layers of both orientations allows the estimation of the layer thickness, the porosity and the interface roughness. High-resolution X-ray diffraction was used to obtain symmetrical and asymmetrical rocking curves, as well as maps of the reciprocal space. The lattice-mismatch parameter was measured and some indications about the pore shape, orientation and size were deduced. The obtained X-ray curves as well as differential scanning calorimetry data are compared to discuss the influence of the substrate orientation on the structural properties of p+-type porous silicon material.