Active Layer Thickness Effects on the On-State Current and Pulse Measurement at Room Temperature on Deposited Zinc Oxide Thin-Film Transistors

Abstract

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 (SiO2) 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 cm2/Vs to 16.40 cm2/Vs and on-to-off current ratios of 108 to 107 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.