Effects of thermal annealing on photoluminescence of Si~+/C~+ implanted SiO_2 films

摘要

The mechanisms of photoluminescence (PL) originating from Si~+/C~+ implanted SiO_2 are still unclear and need to be clarified. Thus, the purpose of this study is to thoroughly investigate the effects of ion implantation and post-annealing temperature on microstructures and PL characteristics of the Si~+/C~+ implanted SiO_2 films. A comparative analysis was also conducted to clarify the different optical properties between the Si~+ and Si~+/C~+ implanted SiO_2 films. In this study, thermally-grown SiO_2 films on Si substrates were used as the matrix materials. The Si~+ ions and C~+ ions were separately implanted into the SiO_2 films at room temperature. After ion implantation, the post-annealing treatments were carried out using the furnace annealing (FA) method at various temperatures (600-1100 ℃) for 1 h in a N_2 ambient. The PL characteristics of the implanted SiO2 films were analyzed using a fluorescence spectrophotometer. The results revealed that the distinct PL peaks were observed at approximately 310, 450 and 650 nm in the Si~+-implanted SiO_2 films, which can be attributed to the defects, the so-called oxygen deficiency centers (ODCs) and non-bridging oxygen hole centers (NBOHCs), in the materials. In contrast to the Si~+ ion implantation, the SiO_2 films which were sequentially implanted with Si~+ and C~+ ions and annealed at 1100 ℃ can emit white light corresponding to the PL peaks located at around 420,520 and 720 nm, those can be assigned to the Si-C bonding, C-C graphite-like structure (sp~2), and Si nanocrystals, respectively. Moreover, a correlation between the optical properties, microstructures, and bonding configurations of the Si~+/C~+ implanted SiO_2 films was also established in this study.