Effects of V/III ratio on photoluminescence spectra of Eu-doped GaN grown by molecular beam epitaxy were investigated. The Eu-related luminescence originating from D-5(0)-F-7(2) transition of Eu3+ was observed in the wavelength range of 620-624 nm under above-gap and below-gap excitations. Two luminescence peaks at 620.3 and 622.2 nm were observed in Eu-doped GaN with the Eu concentration of 1 at% under above-gap excitation, and a single peak at 620.3 nm was observed under below-gap excitation, suggesting multiple incorporation sites of Eu in GaN. The intensity ratio of the two peaks was found to vary with the V/III ratio. It was suggested that the incorporation site of Eu in Eu-doped GaN is sensitive to the V/III ratio. (c) 2006 Elsevier B.V. All rights reserved.