Photoluminescence and electroluminescence of size-controlled silicon nanocrystallites embedded in SiO2 thin films

Silicon nanocrystallites (nc-Si) were obtained by thermal annealing treatments of SiO∕SiO2 multilayers, prepared by evaporation. The nc-Si size was controlled by the SiO thickness. In this study the SiO2 thickness was maintained at 5nm and the SiO thickness was varied from 2to6nm. The film’s microstructure was studied by transmission electron microscopy. A strong photoluminescence was obtained in the visible range which corresponds to the radiative recombination of electron-hole pairs in the nc-Si. The electroluminescence signal is weaker and broader than the photoluminescence one. A model taking into account SiO2 defects and nc-Si is proposed to explain the electroluminescence results.