الفهرس 
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Abstract
Rare-earth-doped wide-bandgap semiconductors are an interesting class of inorganic luminescent materials with complex optical properties and widespread potential applicationsin optoelectronics Undoped and Eu-doped GaN powders have been synthesized by the co-precipitation methodfollowed by nitridation at high temperature.The X-ray diffraction (XRD) patterns evealthe single-phase wurtzite structure of the synthesized undoped and Eu-doped GaN powders. The morphology of the samples was examined by the field emission scanning electron microscope (FE-SEM) and the high resolution transmission electron microscope (HR-TEM), and it was shown thatthe micron-sized particles are composed of agglomerated nano-crystallites.This agglomeration may be due tothe absence of any surfactantduring thepreparation.Under above bandgap excitation,the room-temperature photoluminescence (PL)of both samples show the characteristic GaN band-edge emission peak at 363 nm, as well as a broad defect-related emission band centered at around 415 nm.The Eu-doped GaN sample, under below bandgap excitation at 464 nm, exhibited red emission peaks at 593 nm and 616 nm,corresponding to the 5D0 → 7F1 and5D0 → 7F2 transitions, respectively,within the 4f- observed only under resonant excitati host to Eu 3+ionsin the prepared sample.