We have grown Eu-doped GaN on a freestanding GaN substrate by organometallic vapor phase epitaxy and investigated its red luminescence that is due to intra-4f shell transitions of EU3+ ions. The optimum growth temperature for Eu luminescence was 50 °C higher than that of Eu-doped GaN on a sapphire substrate. The highest emission intensity was more intense than that on the sapphire substrate, while the Eu luminescence lifetime was identical for both substrates. These results indicate that energy transfer from the GaN host to the EU3+ ions occurs more efficiently in Eu-doped GaN on the GaN substrate because of a low dislocation density.
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