Quantum size effects on photoluminescence from Si nanocrystals in PECVD silicon-rich-oxide

Red-shift of photoluminescence (PL) spectra and increasing intensity after subsequent annealing have been observed in plasma-enhanced chemical-vapor-deposition (PECVD) silicon-rich-oxide (SRO). Based on FTIR results, however, PECVD SRO does experience chemical and structural changes during post-deposition annealing and becomes denser. Besides, the enhanced tunneling characteristics of MOS capacitor using SRO thin film as injector due to nanocrystalline silicon (nc-Si) in SRO thin film is also observed. These results strongly suggest the luminescence and the enhanced tunneling characteristics originate from the quantum size effect of nc-Si. In this paper, a Si-island model is proposed to delineate the gradual red-shift phenomenon of PL spectra.