Effect of post-annealing on structural and optical properties, and elemental distribution in heavy Eu-implanted ZnO thin films

Abstract

The effect of post-annealing on ZnO thin films implanted with Eu at 1 × 10¹⁷ ions/cm² was studied to characterize the structural and luminescent properties, and the distribution of Eu in thin films. After post-annealing at 600°C, the broadening of the ZnO(002) diffraction peak was the same as that of the as-implanted sample. The sample showed orange luminescence due to Eu³⁺. After post-annealing at 900°C, a sharp diffraction peak of ZnO(002) was observed. The orange luminescence due to Eu³⁺ had disappeared, and instead, the intense luminescence of the band-edge of ZnO was observed in the sample. Ion images of Zn and Eu indicated that the Eu separated from the ZnO during the post-annealing. It is thought that the difference in luminescence is due to the separation of Eu from ZnO.