Characteristics of nanocrystalline AlN:Er films co-deposited by using AlN, Er, and SiO2 targets

We report the characteristics of AlN:Er films that were co-deposited by using AlN, Er, and SiO2 targets. The PL emission spectra show strong green emissions of Er3+ ions in AlN:Er films annealed at an optimal temperature of 750 °C, which is attributed to the intra-4f Er3+ transitions of 2H11/2 → 4I15/2 and 4F7/2 → 4I15/2. This optimal temperature can activate Er species as an efficient visible luminescence center. High-resolution transmission electron microscopy (HREM) observations showed that the AlN:Er film annealed at 750 °C exhibits the microstructure of AlN nanocrystallites embedded in the amorphous matrix. The occurrence of strong Er3+ emissions in the amorphous–nanocrystalline AlN:Er films by thermal annealing might contribute to an increased number of excitation Er3+ centers and the presence of oxygen related to Er3+ excitation and recombination processes. A distinct visible bluish green emission is also confirmed from the EL device with an amorphous–nanocrystalline AlN:Er active layer.