Abstract-Classically, in the field of photovoltaic, porous silicon (PS) is used as an antireflecting layer, but these last years, we are interested in a new application of this material, which allows, by technologies very different from proceed usual to detach from the singlecrystal thin layers from a substrate. An electrochemical attack is carried out on a silicon substrate, with times and densities of current variable so as to obtain two layers of gradual porosities being formed from surface (strong porosity in-depth). We carry out then a hydrogenation (to passivate the structure), an epitaxy in liquid phase (LPE) or Vapor Phase Epitaxy (VPE), and then we carry out the cell. During the temperature treatment high, porous silicon is recristallized partially. Then separation is made once the cell carried out, by sticking a transparent plastic film on surface and by applying a weak force (the PS being used as sacrificial layer). In this study, a characterization by secondary spectroscopy of mass of the ions (SIMS) informs us about the level of doping and the concentration of the carriers, and, electronic microscopy has sweeping (SEM) informs us about porous morphologies of these layer.