Enhancing the structural, optical and electrical properties of ZnO nanopowders through (Al + Mn) doping

Undoped ZnO and Zn0.97−xAl0.03MnxO (x = 0, 1, 2 and 3%) nanopowders (NPs) were synthesized by co-precipitation method. They were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman, UV–visible, photoluminescence (PL) and impedance spectroscopies. All samples exhibit a single phase wurtzite type. The average crystallite size lying between 22 and 42 nm was found to increase for all doped ZnO samples. The optical transmission in the visible region was improved due to doping. The optical band gap is in the range of 3–3.4 eV and was found to decrease up to 2% of Mn content but slightly increases with further doping. All PL spectra exhibit two emission peaks in UV and visible regions. The deconvolution of the visible emission peak reveals different emissions for all samples. An additional yellow emission is noticed for (Al + Mn) ZnO doped samples suggesting that the incorporation of aluminum and manganese in the zinc oxide host lattice enhances luminescence properties of ZnO. The ac conductivity (σac) was found to follow Jonscher’s power law and was improved with doping. Cole-Cole plots of all samples were suitably fitted to a circuit consisting in a parallel combination of a resistance and a constant phase element (CPE). Keywords: ZnO nanopowder, Doping, XRD, Optical properties, Conductivity

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