Low Operation Voltage InGaZnO Thin Film Transistors with LaAlO₃Gate Dielectric Incorporation

Abstract

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 (Vt) of 0.29 V, a good on-off-state drive current ratio (Ion/Ioff) of 1.1 × 105, and field effect mobility (μFE) of 5.4 cm2/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 Vt 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.