Dynamics and microscopic origin of fast 1.5 μm emission in Er-doped SiO_2 sensitized with Si nanocrystals

摘要

We investigate the origin of fast 1.5 μm photoluminescence from Er-doped SiO_2 sensitized with silicon nanocrystals, which appears and decays within the first microsecond after a short laser excitation pulse. Time-resolved and temperature-dependent measurements on the 1.5 μm emission from Er-doped and Er-free samples reveal that the major part of this emission is Er related. A possible contribution from other photoluminescence bands, specifically of the defect-related band centered around 1.3 μm, has also been considered. All the results obtained indicate the dominant contribution of Er~(3+) ions to the fast 1.5 μm emission in the investigated materials. We propose two possible mechanisms behind the fast excitation and quenching of Er~(3+) 1.5 μm emission, which are both facilitated by Er-related trap centers with ionization energy of E_A≈ 60 meV.