Electrical and electroluminescence properties of silicon nanocystals/SiO2 superlattices

The electrical and electroluminescence (EL) properties of Si-rich oxynitride (SRON)/SiO2 superlattices are studied for different silicon excess and layer thicknesses. The precipitation and crystallization of the Si excess present within the SRON layers is induced by a post-deposition annealing treatment, in order to form Si nanocrystals (Si-NCs). The electrical characterization performed in dark conditions allowed for deducing the charge transport mechanism through the superlattice structure, found to follow the Poole-Frenkel law. In addition, the EL investigation revealed the correlation between EL excitation and transport mechanisms, suggesting that impact ionization of high-energy conduction electrons dominates the whole frame. The reduction of the SiO2 barrier thickness and the increase in the Si excess were found to enhance the carrier transport through the superlattices due to the reduction of the electrons mean free path, which, in turn, modifies the EL properties.