Exploration of Nanowire Photonics Towards Advent of Super-Smart Societies

Herein, the growth and optical characteristics of ZnOZnO/Tm,Yb-codoped ZnOZnO core–shell nanowiresNanowire (ZnO:Tm,Yb/ZnO NWs). The growth conditions of the NWs are optimized by systematically changing the growth temperature, VI/II ratio, and growth duration. Photoluminescence (PL) characterization of the ZnOZnO:Tm,Yb/ZnO NWs with different laser sources is performed to investigate the mechanism of energy transfer between the Tm3+ and Yb3+ ions in the NWs. Resonant excitation of Tm3+ ions at 488 nm results in luminescence from the Yb3+ ions, whereas no luminescence is observed from Yb3+ ions for non-resonant excitation. Furthermore, time-resolved PL characterization of the NWs reveals a shortening of the lifetime of Tm3+ luminescence in the ZnOZnO:Tm,Yb/ZnOZnO NWs, as compared with that in ZnOZnO:Tm,Yb/ZnOZnO NWs. These results demonstrate that energy transfer from Tm3+ to Yb3+ ions in the NWs occurs by down-conversionDown-conversion.