Kinetic oscillations of red photoluminescence from nanocrystalline Si/SiO2 films

Experimental investigations on the red photoluminescence (PL) from nanocrystalline Si (nc-Si) embedded in a SiO2 matrix, fabricated by plasma-enhanced chemical vapor deposition and a subsequent post-treatment, reveal under certain conditions the occurrence of kinetic oscillations. For the red PL between 1.5 and 1.75 eV, the spectral shift and the peak intensity versus annealing times show temporal oscillations. The spectral variations are explained by the growth and decay kinetics of two oxygen thermal donors (TDs) upon annealing. The oscillatory behavior is a pure kinetic one. It reflects the regrowth of oxygen TDs by an autocatalytic process during their decay. Although the source for the autocatalysis is not clear, this PL oscillation adds more evidence that the red PL observed in our system originates from oxygen TDs-related defect states.