Stable and color-tunable fluorescence from silicon nanoparticles formed by single-step plasma assisted decomposition of SiBr4

Abstract

We describe a facile method to synthesize silicon nanoparticles through plasma-assisted decomposition of silicon tetrabromide, a novel precursor for gas phase synthesis. Raman spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analyses demonstrate that the obtained silicon nanocrystals were covered with a silicon oxide layer. The nanoparticles can be easily dispersed in ethanol and the dispersion exhibited stable optical properties for over half a year, showing strong photoluminescence (PL) under ultraviolet irradiation with quantum yields of up to 24%. The PL properties of the nanoparticles were tolerant to hydrofluoric acid (HF) etching. The PL intensity of the nanoparticles was slightly enhanced after removal of the surface oxide layer via HF etching. Replacement of the surface oxide layer with a hydrogen-terminated surface after etching would be one of the possible reasons for this PL enhancement. In addition, we were able to tune the color of PL of the nanoparticles from dark-blue to greenish-yellow by changing the total pressure of the plasma chamber during synthesis. These results indicated that our method could provide us with a simple and practical method to produce silicon nanoparticles.