Light assisted formation of porous silicon investigated by X-ray diffraction and reflectivity

X-ray diffraction and reflectivity measurements have been used to study the effect of light during chemical etching and formation of porous silicon (PS). A general statement is that illumination during chemical etching and formation leads to an increase of both porosity and lattice mismatch of the porous layer, which is attributed to the formation of smaller crystallites. For light assisted formation using standard current density value, a second regime appears for large illumination power. In this regime the modifications induced by light do not take place in the bulk of the PS layer, but at the propagation front. (C) 2002 Elsevier Science B.V. All rights reserved.