Role of surface texturization in the formation of highly luminescent, stable and thick porous silicon films

Porous silicon (PS) films were prepared by anodization on polished and textured substrates of (1 0 0) Si at different current densities for a fixed anodization time of 30 min. Using scanning electron microscopy (SEM), high-resolution X-ray diffractometry (HRXRD) and photoluminescence (PL) decay measurements, we have demonstrated that the texturization of silicon surface is a simple and effective method for the formation of mechanically stable thick porous silicon films. The PS formed on textured substrates exhibits higher porosity, negligible PL decay, better adherence to the substrate and non-fractured surface morphology compared to that formed on polished silicon substrates under the same preparation conditions. The morphology of the PS film as observed by SEM indicates the formation of highly porous vertical layers separating macroscopic domains of nanoporous silicon. The lattice mismatch or strain measurements from HRXRD revealed that a variety of good quality PS films having different strain values (by varying the current density) corresponding to wide range of band gaps suitable for sensor applications can be formed on textured substrate.