X-ray diffraction investigation of n-type porous silicon

High resolution x-ray diffraction has been used to study the effect of doping level and illumination on the formation of n-type porous silicon. For highly doped n+-type porous layers prepared in darkness, an unusual increase of the lattice mismatch with the formation time is observed. When the samples are prepared under illumination, a degradation of the crystal quality, increasing with a decrease of the material doping level, is observed. The possible origins of these effects are discussed.