Bright luminescence from erbium doped nc-Si/SiO2 superlattices

Optical properties of Er doped Si=SiO2 superlattices and SiO=SiO2 superlattices are compared. In the case of Si=SiO2 superlattices with Si layers thicknesses between 2 and 19 nm polycrystalline like Si layers are observed after annealing. The samples show a very weak defect related red room temperature luminescence. No significant enhancement of the Er luminescence could be shown. The SiO=SiO2 superlattices show after annealing the evidence of separated Si nanocrystals and a very strong red room temperature luminescence. The emission wavelength varies between 750 and 850 nm depending on the SiO layer thickness. In this case, a strong enhancement of the Er 3þ luminescence by more than one order of magnitude was observed. Temperature dependent photoluminescence (PL) measurements of the 1:54 l mE r 3þ