In-depth RBS study of optical layers based on nanostructured silicon

The particular structure of porous silicon (PS), which can be described as an amorphous matrix in which silicon nanocrystals are embedded, makes this material very suitable for its use in many different fields, including optoelectronics and biological applications. In the present work, Rutherford backscattering spectroscopy (RBS) measurements and optical characterization are carried out on PS layers in order to determine their in-depth compositional profile, homogeneity, porosity, oxidation degree and overall optical behavior. The experimental results show quite good in-depth homogeneity of the PS layers since only slight porosity and oxidation degree gradients have been observed, further supported by optical measurements. Additionally, RBS measurements were used to confirm the existence of a layer of low porosity at the PS/silicon interface independently of the formation current density.