Studies on the structural, morphological, optical and electrical properties of Al-doped ZnO nanorods prepared by electrochemical deposition

• High quality undoped and Al-doped ZnO thin films were prepared using a simple electrochemical rout.
• Al doping increases the band gap energy values.
• Al-doped ZnO thin films exhibits aligned nanorods arrays for sample obtained at Al ≤ 1 at.%.
• The better photocurrent properties are found for the film with 2% Al doping.
• The addition of the Al changes the nucleation and growth mechanism of ZnO from progressive to instantaneous.

A study about the growth mechanism of zinc oxide (ZnO) nanorods and Al-doped zinc oxide (AZO) electrodeposited from the reduction of hydrogen peroxide in zinc chloride solutions was reported. The variations of the electrochemical, morphological, structural, optical and photoelectrochemical properties of the AZO thin films were investigated in terms of different Al concentration in the starting solution. X-ray diffraction spectra demonstrate that films crystalline with the Würtzite structure with preferential (002) crystallographic orientation having c-axis perpendicular to the substrate. The AZO films obtained forms aligned hexagonal nanorods and depending on the increasing aluminium concentration, the surface morphologies of the films are changed. As Al concentration increased the optical band gap was also found to be increase from 3.31 to 3.45 eV and in the carrier densities from 1.06 × 1018 to 2.91 × 1018 cm− 3 are observed. The blue shift in the band gap energy was attributed to the Burstein-Moss effect. Changes in the photocurrent response are also discussed in the light of Al doping. The amplitude of the photocurrent generated increases steadily from undoped ZnO to the AZO film (2 at.%) going from 21 to 58 μA at 1.0 V.