Cr-doped ZnO prepared by electrochemical deposition

This study demonstrated the preparation of a Cr-doped ZnO wurtzite structure without any impurity phases (metallic Zn, Cr, Zn(OH)₂, ZnCrO₄, etc.) via electrodeposition. The surface morphology, lattice structure, Cr content, chemical binding characteristics, and optical properties of the deposits were examined by field-emission-scanning electron microscopy, X-ray diffraction, inductive coupled plasma mass spectroscopy, X-ray photoelectron spectroscopy, UV-visible spectroscopy, and photoluminescence, respectively. Cr-doped ZnO in the shape of hexangular columns appears when the applied potential is equal to or more positive than -1.2 V_SSCE. The thickness of the deposits was within the range of 1.07-2.25 μm. Cr was in its trivalent state in the ZnO lattice. Both the high concentration of Cr ions in baths and the more negative applied potential impede the formation of the ZnO(002) plane. The redshift of the bandgap of the deposits from 3.31 to 3.18 eV occurs after the introduction of Cr impurity into the ZnO lattice. The photoluminescence results show both UV and visible light emissions from the electrodeposited specimens.