Active layer thickness effects on the on-state current and pulse measurement at room temperature on deposited zinc oxide thin-film transistors

This study reports on the fabrication of thin-film transistors (TFTs) with transparent zinc oxide (ZnO) semiconductors serving as the active channel and silicon dioxide (SiO ₂) serving as the gate insulator. The ZnO films were deposited by radiofrequency magnetron sputtering at room temperature. Moreover, the effects of channel thickness on the structural and pulse current-voltage characteristics of ZnO TFTs using a bottom gate configuration were investigated. As the channel thickness increased, the crystalline quality and the channel conductance were enhanced. The electrical characteristics of TFTs exhibited field-effect mobilities of 8.36 cm ²/Vs to 16.40 cm ²/Vs and on-to-off current ratios of 10 ⁸ to 10 ⁷ for ZnO layer thickness of 45 nm and 70 nm, respectively. The threshold voltage was in the range of 10 V to 31 V for ZnO layer thicknesses from 35 nm to 70 nm, respectively. The low deposition and processing temperatures make these TFTs suitable for fabrication on flexible substrates.