Si Wire Light Emission Changes During Si/SiO x Interface Formation

Photoluminescence (PL), PL excitation, Raman scattering, IR absorption spectra as well as PSi surface morphology, have been studied as a function of Si/SiO x interface formation during PSi ageing in ambient air with the aim to reveal a PL mechanism. It is shown that fresh- prepared PSi layers created at low values of the anodization current Ia is characterized by “red” emission band centered at 1.72 eV, while the samples prepared at higher values of Ia have “orange” PL band centered at 2.00 eV. During oxidation in ambient air two processes take place at the PSi ageing: the oxidation of small size Si nano-crystallites up to their disappearing and the change of silicon oxide composition at the Si/SiO x crystallite surface. These processes initiate changes in PL and PL excitation spectra. The peak position of “red” PL band shifts to the high-energy up to 1.80-1.85 eV while the “orange” band does not change essentially.