Publication: Synthesis and characterization of copper doped zinc oxide rods
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Date
2012-07-01
Authors
Ong, Cheng Shian
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Abstract
In this project, there are two sections of synthesis process: (i) synthesis of undoped ZnO rods and (ii) synthesis of Cu doped ZnO rods. Undoped ZnO rods were successfully synthesized on Si substrates by sol-gel method using zinc nitrate tetrahydrate, Zn(NO3)2.4H2O and methenamine, (CH2)6N4 as precursors. Twin-rod structures of ZnO rods and agglomeration of ZnO rods were observed. Cu doped ZnO rods were synthesized under same condition with additional of cupric acetate monohydrate, Cu(CH3CO2)2.H2O. The effect on the morphology, crystallinity and optical property was studied. From the studied, size, aspect ratio, crystallinity and c-lattice parameter of Cu doped ZnO rods decreased with increasing of Cu dopant concentration, mainly due to the substitution of Cu2+ ions into the ZnO lattice. Besides, the optical band gap of ZnO rods became narrower, i.e. 3.3132eV for 20mol% Cu doped ZnO as compared to 3.3394eV for undoped ZnO rods. This could be attributed to the formation of CuO which has lower band gap energy (1.35eV) than ZnO when the Cu incorporated into the ZnO rods. As compared to undoped ZnO rods, additional emission peak was found at 2.97eV in the PL spectra for Cu doped ZnO rods synthesized with 10mol% Cu concentration and annealed at 650 oC for 2.0h. This emission could be related to the transition of electrons from Ec to Cu acceptor energy level radiatively. From the indications above, it could be concluded that Cu doped ZnO rods were successfully synthesized via sol-gel method using Cu(CH3CO2)2.H2O as dopant precursor.