Ultra-thin films with embedded Si nanocrystals fabricated by electrochemical dissolution of bulk crystalline Si in the transition regime between porosification and electropolishing

We developed a method for fabricating ultra-thin (18–80 nm) light emitting amorphous films with embedded silicon nanocrystals by anodization of bulk crystalline Si in the transition regime between porosification and electropolishing using short mono-pulses of anodization current. The size of the nanocrystals decreased with increasing current density and it was in the range of 3–7 nm with current densities in the range of 130–390 mA cm−2. At the highest current density used the film/substrate interface was very sharp, while at lower current densities the interface contained nanostructured silicon spikes protruding from the substrate into the amorphous film. The samples were characterized by high resolution transmission electron microscopy, Fourier transform infrared spectroscopy and photoluminescence.