Amorphous ZnO Transparent Thin-Film Transistors Fabricated by Fully Lithographic and Etching Processes

Oxide-semiconductor-based thin-film transistors (TFTs), particularly the amorphous ones, are becoming an important emerging technology. Since oxide semiconductors easily form polycrystalline phases, usually more complicated oxide mixtures are needed for growing amorphous phases. In this letter, we report that by simply reducing the thickness, ZnO can be intentionally grown into the amorphous phase. Furthermore, both top-gate and bottom-gate amorphous ZnO TFTs of micrometer scales were effectively implemented using fully lithographic and etching processes. Rather high field-effect mobilities of 25 and 4 cm2 V s and onoff current ratios of > 107 and > 106 were achieved for top-gate and bottom-gate configurations, respectively. © 2007 American Institute of Physics.