Elaboration, by spray pyrolysis, and characterization of ZnMO (M=Mn, Co, Fe) thin films
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Date
2025-11-12
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Université 20 août 1955-Skikda
Abstract
Transition metals TM (Co, Fe, and Mn) doping induced changes in structural and
optical properties of spray deposited ZnO thin films has been studied using X-ray diffraction
(XRD), Raman spectroscopy, ATR-FTIR spectroscopy, UV-visible spectroscopy, and
photoluminescence spectroscopy (PL) respectively.
As a function of TM molar ratio x, XRD patterns revealed a change of crystalline
parameters depending on TM nature. For Co doping, Co3O4 and Zn(OH)2 secondary phases
appeared for x=0.10. for Mn doping, secondary phases such as MnO2 and ZnMnO3 appeared
for x=0.06 while for Fe doping, no secondary phase was observed. These results were
evidenced by Raman spectroscopy and ATR-FTIR spectroscopy. For the three doping
elements, the band gap energy of ZnO varied, as a function of TM molar ratio x depending on
TM nature. For Co doping, the band gap energy of ZnCoO decreased from 3.45 eV, for
x=0.00, to reach a minimal value of 2.67 eV for x=0.08. For Fe doping, the band gap energy
of ZnFeO decreased to reach a minimum of 3.21 eV for x=0.04. Beyond this molar ratio, the
band gap energy stabilized around 3.27 eV. However, for Mn doping, the band gap energy of
ZnMnO increased to reach a maximum of 3.55 eV for x=0.06.
The photoluminescence spectrum of ZnO presented two peaks: an ultraviolet emission
peak around 375 nm and a near infrared emission peak around 754 nm. Photoluminescence
properties of samples depend on the TM nature and the TM molar ratio x. For Fe doping, the
intensity of these two peaks decreased as a function of Fe molar ratio. No other emission
peaks were observed. For Co doping, the intensity of these two peaks decreased as a function
of Co molar ratio, to completely disappear for x=0.10 leaving their place to a red emission
peak attributed to Co based impurities. For Mn doping, the intensity of UV and NIR emission
peaks decreased rapidly for x=0.02. for x=0.04 and x=0.06, these two emission peaks
disappeared leaving their places for a violet, a blue, and a blue-green emissions attributed
respectively to Mn ions, Zni et VZn.
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Keywords
spray pyrolysis, characterization of ZnMO (M=Mn, Co, Fe) thin films