Effect of Al doping on the microstructural, optical and electrical properties of ZnO films

We prepared Al doped ZnO films by spin coating sol–gel method on ordinary glass substrates. The microstructure of the films was evaluated as a function of doping concentration by X-ray diffraction line broadening analysis using convolutional multiple whole profile fitting method. The optical band gap and activation energy of ZnO films were also determined at different aluminum contents and the correlation between band gap and microstructure was investigated. The following changes were observed, with the rise of doping concentration: the dislocation density of films increases from 9.1(5)×10149.1(5)×1014 to 4.1(5)×1015m-2, volume weighted average domain size decreases from 35(2) to 13(2) nm and the band gap linearly increases from 3.307(7) to 3.358(9) eV.

► Al doped ZnO films were prepared by spin coating sol–gel method.
► The microstructure, optical and electrical properties were studied vs. Al content.
► With the rise of doping concentration, the dislocation density and band gap increase.
► The crystallite size of films decreases with doping concentration.
► The correlation between band gap and microstructure was investigated.