A Study of Photoluminescence Properties of Si-Based CeO₂/Tb₄O₇ Superlattices

CeO₂/Tb₄O₇ superlattices were deposited on P type Si wafers by e-beam evaporation technology. Four typical photoluminescence peaks of Tb³⁺ ions which located around 488, 544, 588 and 623 nm were obtained after the superlattices annealing in weak reducing atmosphere at high temperature. It was indicated that CeO₂ films transferred to amorphous state as the valence transition of Ce⁴⁺→Ce³⁺ which was induced by thermal annealing, the energy transfer occurred between Ce³⁺ ions and Tb³⁺ ions, and the Tb³⁺ ions emition could be detected after obtaining the energy from Ce³⁺ ions. A study about the effect of Tb₄O₇ thickness on the superlattices photoluminescence showed that the maximum PL intensity as thickness of Tb₄O₇ films were about 0.5 nm, the concentration quenching might occur because of the energy transfer among the Tb³⁺ ions. The annealing conditions research demonstrated that the maximum PL intensity could be obtained as the superlattices annealed at 1 200 for 2 hour. Further investigation inferred that the concentration of Ce³⁺ ionsOxygen vacancy defects and the distance between Ce³⁺ ions and Tb³⁺ ions play an important role in the annealing process.