Transmission Line Method Analysis on the Electrical Properties of Bi-Layer Channel Oxide Thin Film Transistors with Oxide-Metal-Oxide Electrodes

Amorphous oxide thin film transistors (TFTs) is designed with bi-layer channel structure of SiInZnO/SiZnSnO (SIZO/SZTO). Bi-layer TFTs has excellent characteristics, such as high mobility, excellent on/off ratio, and low sub-threshold swing compared with the single layer TFTs. In the bi-layer structure, electrical properties were improved by the bottom layer of SIZO film with high carrier concentration and the SZTO film of the top layer could improve stability. Source and drain (S/D) electrodes adopt oxide-metal-oxide (OMO) of SiInZnO/Ag/SiInZnO (SIZO/Ag/SIZO) structure to manufacture high performance TFTs. The sheet resistance (R-sh) and contact resistance (R-c) of single layer TFTs and bi-layer TFTs were obtained using transmission line method (TLM), and the bi-layer TFTs exhibited low R-sh and R-c resistances with OMO electrodes. The low R-sh was found to be advantageous to lowering the R-c at the S/D electrodes when the OMO structure was applied to a TFTs as revealed in the outstanding device performances. OMO electrodes provide potential possibility to improve oxide TFT with excellent characteristics.