Study of the electronic properties of Zn0.8-4xHoxOy (0.05 ≤ x ≤ 0.09) by X-ray absorption and photoemission spectroscopy

The electronic structure of Zn0.8-4xHoxOy (0.05 ≤ x ≤ 0.09) was investigated using X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). Samples were prepared by the solid state reaction method. Using X-ray absorption spectroscopy, the investigation of M4,5 absorption edge of Ho revealed that the electronic structure was directly influenced by the Ho concentration in the Zn0.8-4xHoxOy sample whereas the crystal structure properties showed little/no correlation to the substitution of Ho. The electronic structure differs substantially from those of the reference ZnO. The O K-edge spectra suggest that the combination of the Ho with ZnO enhances the effective charge of the O ions. A systematic study on the composition from lower to higher value of Ho dopant showed the blue shift in band gaps and is discussed in the view of the electronic structure of the Zn0.8-4xHoxOy samples. The inverse susceptibility (1/χ) against temperature curves is plotted to identify the magnetic contribution. Those curves indicate that the substitution of Ho into the ZnO compound causes a weaker antiferromagnetic (AFM) interaction.