Er³⁺ photoluminescence properties of erbium-doped Si/SiO₂ superlattices with sub-nm thin Si layers

The effect of varying the Si layer thickness on the Er³⁺ photoluminescence properties of Er-doped Si/SiO₂ superlattice is investigated. We find that as the Si layer thickness is reduced from 3.6 nm down to a monolayer of Si, the Er³⁺ luminescence intensity increases by over an order of magnitude. Temperature dependence of the Er³⁺ luminescence intensity and time-resolved measurement of Er³⁺ luminescence intensity identify the increase in the excitation rate as the likely cause for such an increase, and underscore the importance of the Si/SiO₂ interface in determining the Er³⁺ luminescence properties.