Filling of the pore network of porous silicon layers with Ge and Si has been demonstrated using a chemical vapor deposition (CVD) technique. It is shown that at low growth rate the species are deposited throughout the whole layer which can be completely filled. At high growth rate, the deposition takes place mainly on the top surface leading to pore mouth bridging. Investigation of the experimental data through a model shows that pore filling is a powerful tool for the study of the mechanisms involved in CVD processes at low temperature. ©1995 American Institute of Physics.