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

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 $81±1nF/cm2$⁠. Due to a very small contact resistance, transistors with channel lengths ranging from $100μm$ down to $5μm$ yield a channel-independent, field-effect mobility of $8±1cm2/Vs$⁠, subthreshold slopes of $0.1±0.01V/decade$⁠, low threshold voltages of $0.4±0.1V$⁠, and high on-off current ratios up to $6×107(W/L=400/5μm)$ at 5 V.