Spectral characteristics of carrier transfer from Si cluster to nanocrystal in Si-rich-oxide/SiO2 multilayer films

Abstract

Si-rich-oxide/SiO2 multilayer composite films containing Si clusters and nanocrystals (NCs) have been synthesized by PECVD technique, and the carrier transfer processes from Si cluster to nanocrystal are studied by photoluminescence (PL) spectra. Compared with the references, intense PL is observed in the composite film, which is caused by the combined effect of Si clusters and NCs. Optical excitation is enhanced due to the dense Si clusters, while the carriers generated in the clusters are transferred to the Si–NCs due to their large carrier capture section. The PL excitation spectra shows that the resonance excitation energy is 3.58 eV, which corresponds to the excitation energy level of SiOX shell covering the Si clusters. Double stretched-exponential decay model is used to demonstrate the PL decay processes in the composite film, and the results suggest that the carrier transfer time is about 35.8 μs.