Improvement of Electrical Characteristics of a-InSnZnO TFT Using Hydrogenated Gate Dielectric

We report the bottom-gate configuration thin-film transistors (TFTs) devices using amorphous indium-tin-zinc-oxide (a-ITZO) active channel and hydrogenated gate dielectric with low trap density. The gate insulator of SIOxNy:H was employed as the source of hydrogen to hydrogenate a-ITZO TFTs. The electrical analysis by X-ray Photoelectron Spectroscopy (XPS) showed that a peak appeared at the binding energy of 530 eV. For non-hydrogenated insulator film, the ratio of O-lattice/O-vacancy was 12.6 while that of hydrogenated insulator film was 14.1. The total peak area of hydrogenated insulator film was as large as 1.31 times. This indicates that the SiOxNy:H insulator properties have been improved by adding the hydrogen. The hydrogenated TFTs exhibited higher field-effect mobility (mu(FE)) of 47.01 cm(2)/V . s compared to the TFT devices without hydrogenation (mu(FE) = 15 cm(2)/V . s). After ammonia (NH3) plasma treatment, the devices showed excellent electrical properties, such as high mu(FE) of 68.36 cm(2)/V . s and large on/off current ratio of 10(8). The enhancement of the hydrogenated TFTs performance is attributed to the passivation of a-ITZO/dielectric interface states and doping of the channel by the hydrogenation effect.