X-ray reflectometry is used to study the first stages of formation of thin n-type porous silicon layers. Results on classical n-type porous silicon prepared under illumination are first reported. Then, the effect of the illumination during the formation is observed by comparing n~(+/-)-type samples prepared in darkness or under illumination. X-ray specular reflectivity measurements allow to observe an increase of the surface porosity even for the short formation times and a macroporous layer under the nanoporous layer is also identified for illuminated samples. The presence of a crater at the top of the layer is observed by profilometer measurements, especially in the case of illuminated samples. Specular and diffuse x-ray scattering results show important effects of light during the porous silicon formation.
展开▼
