Investigation of the Stability and the Transparency of Oxide Thin Film Transistor with bi-Layer Channels and Oxide/Metal/Oxide Multilayer Source/Drain Electrodes

An amorphous oxide thin-film transistor (TFT) is designed with a bi-layer channel of SiInZnO/SiZnSnO (SIZO/SZTO). In the bi-layer structure, the bottom layer of conductive SIZO film with a high carrier concentration and the top layer of semiconducting SZTO film improve mobility and stability. Negative bias temperature stress (NBTS) has been conducted to analyze the stability of the device. In the case of bi-layer TFT, the hump phenomenon was also found in the subthreshold region due to the conductive bottom layer of SIZO with high carrier concentration. The oxide-metal-oxide (OMO) structure of SiInZnO/Ag/SiInZnO (SIZO/Ag/SIZO) was used as source and drain (S/D) electrodes to enhance the electrical and optical properties of highly transparent TFT, mainly due to the wide bandgap and low resistance.