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High purity, strong luminescent gallium nitride (GaN) powders were synthesized by direct reaction of gallium (Ga) and ammonia (NH3) using bismuth (Bi) as a catalyst in a vertical furnace. The reaction rate and yield from metal Ga were improved dramatically in the presence of Bi. In this simple apparatus, 25g Ga can be fully, stoichiometrically converted into GaN within 5 hours. The optimum temperature, NH3 flow rate and reaction time in this hot wall tube furnace were 1000 °C, 500 standard cubic centimetres per minute (sccm) and 5 hours, respectively. X-ray diffraction demonstrates that the material has a high purity and a single crystalline structure. Electron microscopy was used to characterize the morphology of the powder particles. Powder purity was analyzed by utilizing Glow Discharge Mass Spectrometry (GDMS). Cathodoluminescence (CL) data showed strong luminescence from the powder. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
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