Applicability of the polymeric precursor method to the synthesis of nanometric single- and multi-layers of Zn1−xMnxO (x = 0–0.3)
Polymeric precursor method (Pechini) was employed to fabricate single- and multilayers of Zn1−xMnxO (x = 0–0.3) on glass substrates. X-ray diffraction measurements revealed that crystal structure of Zn1−xMnxO multilayers is the typical hexagonal würzite structure of pristine ZnO. A reduced peak intensity and widened full width half maximum (FWHM) value of prominent peaks suggested that the Mn2+ ions have substituted the Zn2+ ion without changing the würzite structure of pristine ZnO up to Mn concentrations x ≤ 0.2. A distinct redshift of the absorption edge was observed as the Mn concentration x was increased. Additionally, the absorption edge was less sharp due, probably, to s–d and p–d interactions, which give rise to band gap bowing. Nevertheless, amorphous states appearing in the band gap as a consequence of reduced crystallinity may also be responsible for the shrinking of the band gap in this material. Interestingly, the field dependence of the magnetization showed typical paramagnetic behavior for all the chosen Mn concentrations with no evidence of ferromagnetic ordering. Probably, the absence of ferromagnetism in the studied Zn1−xMnxO films is strongly related to defects (say Mn impurities at the interface between nano-crystallites) in ZnO due to partial substitution of host Zn ions by Mn ions.