Sensitizing properties of luminescence centers on the emission of Er³⁺ in Si-rich SiO₂ film

In this paper, we report on the luminescence-center (LC)-mediated excitation of Er³⁺ as a function of annealing temperature in Er-doped Si-rich SiO₂ (SRO) films fabricated by electron beam evaporation. It is found that the annealing temperature has significant effects on the emission of Er³⁺ and the specific optical-active point-defects called LCs within Er-doped SRO films. Different luminescence centers generated by the evolution of microstructures during annealing process act as efficient sensitizers for Er³⁺ in the films when the annealing temperature is below 1100 °C. Moreover, the temperature dependence of the energy coupling between LCs and Er³⁺ demonstrates the effective phonon-mediated energy transfer process. In addition, when the annealing temperature reaches 1100 °C, the decreased density of activable erbium ions induced by the aggregation of Er will bring detrimental effects on the emission of Er³⁺. It is demonstrated that an appropriate annealing process can be designed to achieve efficiently enhanced emissions from Er³⁺ ions by optimizing the density of LCs and the coupling between Er³⁺ and LCs.