Electroluminescence from light-emitting devices with erbium-doped TiO_2 films: Enhancement effect of yttrium codoping

摘要

We have recently reported erbium (Er)-related visible and near-infrared (～1540nm) electroluminescence (EL) from the light-emitting device (LED) with a structure of ITO/TiO_2 Er/SiO_2/Si in which TiO_2 :Er refers to the Er-doped TiO_2 film [Zhu et al., Appl. Phys. Lett. 107, 131103 (2015)]. In this work, we codope yttrium (Y) into the TiO_2 :Er film in the aforementioned LED to achieve the significantly enhanced Er-related visible and ～1540nm EL. It is suggested that the Y-codoping leads to a less symmetric and distorted crystal field around the Er~(3+) ions incorporated into the TiO_2 host, thus increasing the probabilities of intra-4/ transitions of Er~(3+) ions. Moreover, the Y-codoping facilitates the dispersion of Er~(3+) ions into the TiO_2 host, which is favorable for reducing the concentration quenching effect on the Er-related EL. For the aforementioned two reasons, the EL from the LED based on the TiO_2 :Er film can be enhanced by means of codoping Y into the TiO_2 host.