Low operation voltage InGaZnO thin film transistors with LaAlO₃ gate dielectric incorporation

In this paper, we report low operation voltage indium gallium zinc oxide (IGZO) thin film transistors (TFTs) incorporating a high-κ lanthanum aluminum oxide (LaAlO₃) as gate dielectric. Good TFT characteristics were achieved simultaneously, including a small subthreshold swing (SS) of 98 mV/dec, a low threshold voltage (V_t) of 0.29 V, a good on-off-state drive current ratio (I_on /I_off) of 1.1 × 10 ⁵, and field effect mobility (μ_FE) of 5.4 cm ²/V · sec. These good performances are related to the high gate capacitance density and small equivalent oxide thickness (EOT) provided by the high-κ LaAlO₃ dielectric. Moreover, the effects of oxygen partial pressure during IGZO deposition process on the device characteristics were investigated. The small SS and low V_t allow the devices to be used at operation voltage as low as 1.5 V, which shows the great potential for future high speed and low power applications.