Hydrogen Diffusion and Threshold Voltage Shifts in Top-Gate Amorphous InGaZnO Thin-Film Transistors

The quality and stability of thin-film transistors (TFTs) applied to large-scale displays are crucial to their successful manufacture and commercial applicability. This article introduces a TFT manufacturing process in which the source/drain system is defined by hydrogen doping in the dielectric layer of the top-gate amorphous indium gallium zinc oxide (a-IGZO). A size effect related to this system exists where longer channels allow a greater amount of hydrogen to diffuse into the center of the channel. For shorter channels, this results in a lower energy barrier and a shift in the threshold voltage. A physical mechanism model is proposed to verify the abnormal electrical characteristics caused by hydrogen diffusion into the top-gate a-IGZO. The insights provided by these results can be used to further develop TFTs for use in large-scale display applications.