Microstructure and optical properties of porous silicon after plasma assisted nitridation

Porous silicon samples have been subjected to plasma treatments under ammonia atmosphere. The samples were characterized by IR, UV-Visible reflectance and stationary photoluminescence spectroscopies. A deep modification concerning both surface and bulk properties of silicon nanocrystals is clearly observed. In particular, the nanocrystals surface is covered by amino groups, as checked by IR spectroscopy, whilst bulk modification can be inferred by UV-Visible reflectance and luminescence characterizations, in particular for high porosity. The results demonstrate that plasma assisted nitridation yields to a controllable modification of the optical and chemical properties of porous silicon, without need of thermal annealing and/or wet chemical processes.