Low-voltage zinc-oxide thin-film transistors on a conventional SiO2 gate insulator grown by radio-frequency magnetron sputtering at room temperature

In this paper we present bottom-gate-type ZuO-based TFTs with low threshold voltages fabricated with a conventional SiO2 gate insulator by radio-frequency (RF) magnetron sputtering at room temperature. The SiO2 is used as a gate insulator, and it is possible to achieve a low gate leakage current (< 10 pA) by using this conventional SiO2 oxide without new gate oxide materials. The ZnO film also has good uniformity and transparency. The ZnO TFTs operate in the enhancement mode with a threshold voltage of 2.5 V. A mobility of 0.018 cm(2)/(V.s), an on/off ratio of about 10(4), and a gate voltage swing of 1.7 V/decade are obtained. We successfully demonstrate that a ZnO TFT with comparable electrical characteristics can be fabricated by utilizing the conventional SiO2 gate insulator. It is also possible to reduce the power consumption due to their low threshold voltage and low leakage current.