Ultraviolet free-exciton light emission in Er-passivated SnO2 nanocrystals in silica

SnO2 nanocrystals are grown in silica starting from a sol-gel method and using Er doping to passivate the cluster boundaries. As a result, emission at 3.8 eV from the decay of SnO2 free excitons is observed in nanostructured SnO2:SiO2, besides the extrinsic 2 eV luminescence of defects in SnO2 and ascribable to substoichiometric nanocluster boundaries. The analysis of the extrinsic emission competitive with the ultraviolet (UV) luminescence evidences the involvement of a phonon mode at 210 cm(-1) from a SnO-like phase. The feasibility of passivated wide-band-gap nanocrystals in silica gives interesting perspectives for UV-emitting optical devices. (c) 2006 American Institute of Physics.