Top-gate amorphous IGZO thin-film transistors with a SiO buffer layer inserted between active channel layer and gate insulator

In this paper, top-gate thin-film transistors (TFTs) using amorphous In–Ga–Zn–O as the n-channel active layer and SiO2 as gate insulator were fabricated by radio frequency magnetron sputtering at room temperature. In this device, a SiO layer was used to be a buffer layer between active layer and gate insulator for preventing the damage of the InGaZnO surface by the process of sputtering SiO2 with relatively high sputtering power. The thickness of buffer layers was studied and optimized for enhancing the TFTs performances. Contrasting to the TFTs without buffer layer, the optimized thickness of 10 nm SiO buffer layer improved the top-gate TFTs performances greatly: mobility increases 30%, reached 1.29 cm2/V s, the Ion/Ioff ratio increases 3 orders, and the trap density at the interface of channel/insulator decreases about 1 order, indicated that the improvement of semiconductor/dielectric interface by buffering the sputtering power.

► We firstly use SiO as buffer layer above the channel layer reducing the surface damage by sputtering.
► The insulator was either polymer or fabricated by PECVD, which using the toxic processing gases.
► Contrast to the TFTs without SiO, the mobility enhanced 30%, Ion/Ioff increases about 3 orders.