Synthesis of Rare-Earth Doped and Undoped GaN Nano-Crystallites

Undoped and Eu3+-doped GaN crystallites have been synthesized by the co-precipitation method followed by nitridation reaction at 1100 degrees C for 2 h, under a continuous flow of NH3 gas. X-ray diffraction patterns (XRD) revealed that the synthesized undoped and Eu3+-doped GaN crystallites are of a single-phase wurtzite structure. The morphology of the samples was examined by field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HR-TEM), and it was shown that the micron-sized particles are composed of agglomerated nano-crystallites. Under the above band gap excitation, all samples exhibited room-temperature photoluminescence with the characteristic GaN band-edge emission peak centered at 363 nm (similar to 3.4 eV, FWHM similar to 10 nm) as well as broad defect-related emission peak centered at about 405 nm. The Eu-doped GaN sample, under below bandgap excitation, exhibited red emission peaks centered at 593 nm and 616 nm corresponding to the D-5(0) -> F-7(1) and D-5(0) -> F-7(2) transitions, respectively, within the 4f shell of Eu3+ ions.