The wide band gap of highly oriented nanocrystalline Al doped ZnO thin films from sol–gel dip coating

Undoped and Al doped ZnO thin films were prepared on glass substrate by sol–gel dip coating from PVP-modified zinc acetate dihydrate and aluminium chloride hexahydrate solutions. The XRD patterns of all thin films indexed a highly preferential orientation along c-axis. The AFM images showed the average grain size of undoped ZnO thin film was about 101 nm whereas the smallest average grain size at 8 mol% Al was about 49 nm. The values of direct optical band gap of thin films varied in the range of 3.70–3.87 eV.