Low-voltage InGaZnO thin-film transistors with Al₂O₃ gate grown by atomic layer deposition

Abstract

We report on low-voltage, high-performance amorphous indium gallium zinc oxide n-channel thin-film transistors fabricated using 100-nm-thick Al₂O₃ grown by atomic layer deposition as the gate dielectric layer. The Al₂O₃ gate dielectric shows very small current densities and has a capacitance density of 81±1 nFcm². Due to a very small contact resistance, transistors with channel lengths ranging from 100 μm down to 5 μm yield a channel-independent, field-effect mobility of 8±1 cm² V s, subthreshold slopes of 0.1±0.01 Vdecade, low threshold voltages of 0.4±0.1 V, and high on-off current ratios up to 6 x10⁷ (WL=4005 μm) at 5 V.