Comparative optical study of Eu~(3+) ions doping in InGaN/GaN quantum dots and GaN layer grown by molecular beam epitaxy

摘要

We report on a comparative optical study of InGaN:Eu quantum dots (QDs) and GaN:Eu layer grown by molecular beam epitaxy (MBE). Analysis of the ~5D_0 → ~7F_2 transition as a function of the excitation wavelength shows that Eu~(3+) ions in InGaN:Eu QDs are located inside InGaN QDs and also in the GaN barrier layer. The existence of Eu~(3+) ions in the GaN barrier layer is explained by Eu segregation/diffusion during growth. For Eu~(3+) ions located inside InGaN QDs the photoluminescence (PL) shows only a slight decrease with temperature from 5 K to 300 K. In contrast, the PL from Eu~(3+) ions in the GaN barrier layer or in GaN thick layer shows a much more pronounced thermal quenching.