Defect-related photoluminescence of silicon nanoparticles produced by pulsed ion-beam ablation in vacuum

Visible light emission has been observed from Si nanoparticles produced using an intense pulsed ion-beam evaporation (IBE) technique in vacuum. The as-prepared Si nanoparticles possess good crystallinity without any post-annealing. Room-temperature photoluminescence (PL) spectra for the Si nanoparticles were registered in blue-green range. The average crystal size (around 20 nm) estimated from glancing angle X-ray diffraction (GAXRD) was relatively large, inconsistent with quantum size effect for the light emission. The Si nanoparticles was exposed to O2 gas at elevated temperature and hydrofluoric acid (HF) vapor at room temperature for examining the PL source, where significant deterioration of PL intensity was found subsequently. Combined with analyses of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX), the PL is attributable to oxide defects of the samples.