| With the development of science and technology, the existing microelectronic technology has been difficult to meet the higher requirements put forward by the modern electronic technology which was supported by microelectronic technology. Using photons to instead of electrons as the carrier of information, that microelectronic technology turn into photon integrated or optoelectronic integrated technology become an inevitable trend. The Ⅲ-Ⅴ semiconductor materials are suitable to use for optoelectronic devices, however the technology to manufacture large-scale electronic integrated circuit is still immature for the Ⅲ-Ⅴ compound materials and the cost too high to enter the civilian market. In contrast, the manufacturing process of silicon-based microelectronic integration is quite mature and it has reached the level of large-scale industrial production. So. the silicon-based optoelectronic integration becomes the main interest point of the study. The silicon semiconductor materials, however, is not good at luminescence which limits their application for the optoelectronic integration. Rare earth ions own a wealth of electronic energy levels and the4f electron transition characteristics. So. the rare earth ions can obtain a variety of luminescence properties to be able to be used as luminescence materials for high level technology especially the field of communication. The rare earth doped silicon-based luminescence materials embedded Si-nc have been the relentless pursuit of research goals for great significance shown in the development from microelectronic technology to photon integrated or optoelectronic integrated technology.In this thesis, Er-doped Si-rich silicon oxide samples and Ce-doped silicon oxide samples were successfully prepared, respectively, by ion beam sputtering and ion implantation. The microstructure and photoluminescence (PL) properties of Er-doped Si-rich silicon oxide samples were investigated through transmission electron microscopy (TEM), Raman spectroscopy and PL spectroscopy, respectively. The PL properties of Ce-doped silicon oxide samples were also investigated via the PL spectroscopy. And the photoelectric properties of doped SiO2thin films were studied by CASTEP software package.The Er-doped Si-rich silicon oxide samples were annealed at1100℃with annealing time from10sees to5mins. The investigations of the microstructure and PL properties show that Si nanocrystalline (Si-nc) was formed in annealed samples and PL of Si-nc and Er3+ions were observed at room temperature from all annealed samples. The size of Si-nc particle increases with increasing annealing time. So, the quantum confinement effect becomes weak leading to the decrease of PL intensity and red shift of PL peak wavelength. In contrast, there is no obvious change of the PL peak position of Er3+ions with increasing annealing time. However, the PL intensity changed as the annealing time increased, and the changing trend is contrary to that of Si-nc which verifies the energy transfer does exist between Si-nc and Er3ions. Different pressures were applied to the samples and the PL studies show the peak position changed sharply as the pressure reached5.76GPa, the PL intensity was also changed as the pressure value is around5.76GPa. All the changes may arise from the change of the structure of matrix materials.Two series Ce-doped silicon oxide samples were successfully prepared via different processes. PL of Ce3+ions were observed at room temperature from all unannealed and annealed samples. PL of Ce3+ions were detected from all Ce-doped silicon oxide samples un-annealed and annealed and the effect of Ce ions concentrations, annealing conditions and fabricating process on the PL properties were investigated comprehensively. The results indicated that the PL properties were dependent strongly on Ce ions concentrations, annealing temperatures, annealing ambient and fabricating process. The PL intensity increases almost linearly and the peak position changes with increasing Ce concentrations. As the Ce concentrations further increased, the distance between Ce3+ions decreased, some excited Ce3+ions transfer their energy to other nearby Ce3+ion, which causes PL quenching. When the samples were annealed at high temperatures in air ambient, the amount of Ce3+ions increases and more Ce3+ions have enough energy to enter the network of silica to form the PL centers, so the PL intensity enhanced. However, the PL intensity decreases obviously as the annealing temperatures continue to increase. The Clustering or precipitation of Ce3+ions occurs and Ce3+ions can be oxidized to form inactive Ce4+ions at higher temperatures, which results in a decrease of PL intensity. Compared the PL spectroscopy of samples annealed in different ambient, the results indicated nitrogen gas can protect the Ce3+ions from being oxidized. Therefore, the PL intensity can be enhanced for the samples annealed in nitrogen gas. The fabricating processes also have an influence on the PL properties. The oxidation of the samples with Ce ions implanted into Si films likely produces more Ce4+, leading to a PL quenching which is not observed in the samples with Ce ions implanted into SiO2films.The electronic structure and optical properties of Si-nc embedded in SiO2and Ce-doped SiO2were investigated by first-principles pseudopotential plane-wave method. The results show the whole conduction band moved down and the localized energy levels near the Fermi level were observed in the Si-nc embedded in SiO2. And the band gap changed from5.742eV to1.05eV. According to the absorption spectroscopy, the new absorption peak at about2.27eV is attributed to the transition of the electrons from-1.01eV energy level to1.05eV energy level generated by valence-band distortion. As for the Ce-doped SiO2structure, the results show the impurity levels of Ce were introduced leading to the decrease of band gap. The absorption peak at about2.96eV is attributed to the transition of electrons from4f energy level to5d energy level, which consisitent the measurement result. |
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