High field-effect mobility amorphous InSnZnO thin-film transistors with low carrier concentration and oxygen vacancy

The influence of carrier concentration and oxygen vacancy on the performance of amorphous-indium-tin-zinc-oxide (a-ITZO) thin-film transistors (TFTs) is reported. The ITZO TFT with lowest carrier concentration and oxygen vacancy has a high field-effect mobility (μ_FE) of 37.2 cm²/V·s, a high on/off current ratio (I_ON/I_OFF) of ~1 × 10⁷ and a low subthreshold swing (SS) of 0.93 V/decade. By increasing the carrier concentration and oxygen vacancy, μ_FE, I_ON/OFF and SS were surprisingly degraded to 14.4 cm²/V·s, ~4 × 10⁴ and 4.01 V/decade, respectively. By controlling the carrier concentration and oxygen vacancies of ITZO bulk, improvement of the performance in TFT devices can be achieved. The proposed high μ_FE of 37.2 cm²/V·s is enough for the application of next-generation displays requiring ultra-high resolution and high-frame-rate displays.