Effect of buffer layer on solution deposited ZnO films

ZnO films were prepared by solution deposition method on various substrates: bare glass, TiO2-buffer-coated glass, ITO glass and ZnO-buffer-coated glass. PEG addition was used to further investigate the effect of the patterned ZnO buffer on the morphology of the films. The structural morphology was investigated by using X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy analysis methods. The nature of the substrate was found to have effect on the morphology and crystal structure of the resultant films. All the films deposited on various substrates were c-oriented and the highest intensity of (002) diffraction peak appeared in the samples deposited on ZnO buffer. Addition of PEG to the buffer precursor affected the size distribution of ZnO grains on buffer layer, resulting in composite films with nano- and microcrystals which dispersed in each other. The homogeneous nucleation and heterogeneous nucleation on the two sides of the substrates were discussed based on the film morphology.