Low-voltage InGaZnO thin-film transistors with Al2O3 gate insulator 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 6×107 (W/L=400/5 μm) at 5 V.