Samah Mohamed Hamdy Ahmed creator Lotfia Elnadi Supervisor Mostafa Elsayed Supervisor Yahia Badr Supervisor text theses ua Cairo Samah Mohamed Hamdy Ahmed 2013 monographic eng

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170 P. : charts , facsimiles ; 25cm Rare-earth-doped wide-bandgap semiconductors are an interesting class of inorganic luminescent materials with complex optical properties and widespread potential applications in optoelectronics. Undoped and Eu-doped GaN powders have been synthesized by the co-precipitation method followed by nitridation at high temperature. The X-ray diffraction (XRD) patterns reveal the 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 that the micron-sized particles are composed of agglomerated nano-crystallites. This agglomeration may be due to the absence of any surfactant during the preparation. 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 {u2192} ⁷F₁ and ⁵D₀ {u2192} ⁷F₂ transitions, respectively, within the 4f-shell of Eu³⁺ ions ions specialized Samah Mohamed Hamdy Ahmed ; Supervised Mostafa Elsayed , Lotfia Elnadi , Yahia Badr Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Science and Interaction Issued also as CD Rare-earth ions Semiconductors Zinc oxide http://172.23.153.220/th.pdf http://172.23.153.220/th.pdf EG-GiCUC 141102 20250223031102.0 eng