Bulk silicon is the material for microelectronics fabrication such as memory device. However, its optical properties are poor due to its indirect band gap. Since the photoluminescence from porous silicon at room temperature was first reported by Canham, silicon nanostructures have attracted considerable interest due to their potential applications in optoelectronic devices such as Si-based LEDs, solar cell. In the present study, the nanocrystalline silicons were synthesized by non-thermal plasma from gas phase. And Nitrogen plasma was applied to reduce the nonraidative recombination center which related to the emission efficiency. To confirm the effect of nitrogen plasma, the compositional, electrical and optical analysis of silicon nanocryatals layer were also investigated.