Characteristics of Flexible Thin-Film Transistors With ZnO Channels

In this paper, we demonstrate the fabrication of ZnO-based thin-film transistors (TFTs) on flexible substrates (polyethylene terephthalate) through radio-frequency sputtering and low-temperature procedure. The device structure belongs to bottom-gate type TFTs where ZnO and HfO₂ are used as channel and gate dielectric layer, respectively. XRD results show that the ZnO channel layers are hexagonal wurtzite structure with (002) orientation. The properties of the fabricated devices are also characterized within several environmental and physics conditions. It can be found that the flexible TFT device is with a low operating voltage and high current ON/OFF ratio; the gate leakage current and transparency are found to be ~12 nA and 75%, respectively. The gate leakage current (IG), drain-source current (IDS), ON/OFF current ratio (I_ON/OFF), threshold voltage (V_th), and field-effect mobility (μ_FE) are measured under different bending modes.