Microstructure Evolution of AlN:Eu Films at Different Annealing Temperatures

Abstract

The microstructure evolution of AlN implanted with Eu during thermal treatment is characterized by transmission electron microscopy (TEM), high‐resolution X‐ray diffraction, and atomic force microscopy. Three regions with different contrast can be observed in the TEM for the implanted samples. The region A is 30 nm below the surface, the region B is about 30–100 nm below the surface and is the worst damaged area, and the region C is the area below the region B. There is a relatively large stress in the region B due to the large radius difference between Eu and Al ions. After annealing at 750 °C, the stress in region B is only partially released outward, resulting in the increase of lattice defects in regions A and C. Both A and C regions show the same contrast in the weak‐beam bright‐field image. After annealing at 1040 °C, there are almost no shadow regions, which indicates that the stress is completely released and the lattice damage is removed. Meanwhile, the results of cathodoluminescence (CL) show that the luminescence of Eu3+ is improved along with the stress releasing and damage removal.