Solution-Processed Zinc Oxide Thin Films and Top-Gate Thin Film Transistors

ZnO thin films were prepared by spin-coating the precursor solution with different concentrations. The morphologies and crystallinity of the ZnO films were characterized by Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD). Multilayer ZnO films were employed as active layers to prepare thin film transistors (TFTs), and patterned indium tin oxide (ITO) was used as source and drain electrodes. The device based on the three-layer ZnO films, prepared with the precursor concentration order of 0.25, 0.10 and 0.05 mol.L-1, showed higher mobility of 7.1 x 10(-3) cm(2).V-1.s(-1) than the device with the precursor concentration order of 0.05, 0.10 and 0.25 mol.L-1 (5.2 x 10(-3) cm(2).V-1.s(-1)). The difference of the performance of TFTs based on these two kinds of films Is attributed to the roughness of the multilayer ZnO thin films. Smooth film is useful for forming excellent semiconductor/insulator interface, resulting in high mobility.