Annealing induced reorientation of crystallites in Sn doped ZnO films

• A novel annealing induced reorientation of crystallites in favour of (1 0 0) plane is reported.
• Ostwald ripening effect is realized through X-ray diffraction studies and the findings are confirmed by AFM and PL studies.
• (1 0 0) Preferential orientation in ZnO films suitable for non-linear optical applications is achieved.

Tin doped ZnO thin films were prepared by employing a simplified spray pyrolysis technique using a perfume atomizer and subsequently annealed under different temperatures from 350 °C to 500 °C in steps of 50 °C. The structural, optical, electrical, photoluminescence and surface morphological properties of the as-deposited films were studied and compared with that of the annealed films. The X-ray diffraction studies showed that as-deposited film exhibits preferential orientation along the (0 0 2) plane and it changes in favour of (1 0 0) plane after annealing. The increase in crystallite size due to annealing is explained on the basis of Ostwald ripening effect. It is found that the optical transmittance and band gap increases with increase in annealing temperature. A slight decrease in resistivity caused by annealing is discussed in correlation with annealing induced defect modifications and surface morphology.