Theory for photoluminescence from SiO2 films containing Si nanocrystals and Er ions

Abstract

In this article, the reported experimental phenomena of energy transfer from Si nanocrystals (nc-Si) to Er ions inside the SiO2 surrounding the nc-Si or at the nc-Si/SiO2 interface, and the origin of the characteristic double photoluminescence (PL) peaks in the SiO2 film containing nc-Si and Er ions [Fujii et al. Appl. Phys. Lett. 71, 1198 (1997)] are explained by means of the quantum confinement–luminescence center model. The theoretical results show that the PL peak at 0.805 eV is caused by a recombination process outside the nc-Si, i.e. the electron–heavy-hole pairs tunnel into the SiO2 barrier, are absorbed, and then recombine radiatively in the Er ions. The PL peak at 1.53 eV most probably originates mainly from another type of defects or impurities in the SiO2 barrier or at the nc-Si/SiO2 interface. The experimental results, that as the concentration of Er ions increases the intensity of PL peak at 0.805 eV increases while the intensity of PL peak at 1.53 eV decreases, have been explained.