Alkaline earth metal ion doping to enhance the light emission from Er3+:SnO2 nanocrystal Co-doped silica films

Alkaline earth metal ions (Mg2+, Ca2+, Sr2+) have been introduced into Er3+:SnO2 nanocrystal co-doped silica thin films fabricated by a sol-gel method combined with a spin-coating technique. It is found that the incorporation of alkaline earth metal ions can enhance the light emission from Er3+ at the wavelength around 1540 nm and the strongest enhancement is observed in samples doped with 5 mol% Sr2+ ions. Based on X-ray diffraction, X-ray photoelectron spectroscopy and other spectroscopic measurements, the improved light emission can be attributed to more oxygen vacancies, better crystallinity and a stronger cross-relaxation process with the introduction of alkaline earth metal ions.