Abstract
Zn 1− x Mn x O sub-micron fibrous thin films were synthesized by a simple sol–gel dip-coating technique. XRD pattern confirmed the hexagonal wurtzite structure of the synthesized material. Expansion of the c-axis lattice parameter has been observed with the increase of manganese content in the films. Manganese content ( x) in the films varied from 0.0098–0.0568 and was determined by energy-dispersive X-ray analysis. The average diameter of the ZnO fibers were ∼700 nm whereas the length was several hundred micro-meters and hence the aspect ratio was quite large (>150). Branching and uneven growth occurred with the increase of manganese content as is evident from SEM analysis. Optical transmittance spectra showed absorption band due to characteristic d–d transition of Mn 2+ ions nearly at 3 eV. The band gap, as determined from the transmittance spectra, decreased to 3.28 eV for x = 0.0287 and then increased upto 3.38 eV for x = 0.0568 as compared with the undoped film for which the band gap is 3.31 eV. Photoluminescence spectra of Zn 1− x Mn x O fibrous thin films on glass substrate for different doping levels were also studied which showed a broad UV band at ∼397 nm, a narrow blue–green band at ∼466 nm and another broad peak at ∼526 nm. Mn doping causes a large reduction in the intensity of the UV emission and small reduction in green emission intensity of the PL spectra.
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