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.