Surface eu-treated ZnO nanowires with efficient red emission

Abstract

The structural and optical properties of post surface Eu-treated ZnO nanowires (NWs) have been investigated systematically. It is found that the Eu3+ ions are in the Eu2O3-like state located at the surface of ZnO NWs. Sharp intense red emissions in the range of 580−650 nm due to the intra-4f transition of Eu3+ ions are observed from the sample. The temperature-dependent photoluminescence (PL) measurement shows that the intensity of the Eu3+ ions emission is related to the near-band-edge (NBE) emission of ZnO NWs, indicating direct energy transfer from ZnO to Eu3+ ions. Finally, the time-resolved PL measurement was carried out, and the roles played by the Eu2O3-like layers are discussed in detail. It is found that the Eu2O3 layers not only suppress the deep level emission (DLE) in ZnO NWs but also provide efficient energy trap centers supporting the direct energy transfer from ZnO to Eu3+ ions.