Highly luminescent ultra small Cu doped ZnO nanostructures grown by ultrasonicated sol–gel route

Highly luminescent ultra small copper doped ZnO nanostructures were synthesized by ultrasonicated sol–gel route. Self assembled nanostructures were obtained on glass substrates using spin coater. The samples were characterized by XRD, AFM, Optical transmission, PL, FTIR and magnetic studies. Continuous ultrasonication helped in obtaining ultra small nanostructures. Observation of weak broadened peaks in X-ray diffractograms indicates the formation of nanocrystal of very small size ZnO. AFM micrographs show assembling of particles in linear direction resulting in formation of nanowires with increasing Cu concentration. The strong blue shift in the optical band gap of copper doped ZnO from 3.2 to 4.76 eV confirms the ultra small size of particles. Doping of copper not only improves the photoluminescence peak in UV region but also results in strong yellow, green and blue luminescence peaks. Undoped ZnO exhibits the diamagnetic behavior, however for higher doping concentration weak ferromagnetic phase observed. Strong green luminescence with weak ferromagnetic properties of ZnO nanowires makes them suitable for magnetic, optoelectronic and biological sensing devices.

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