Mist CVD deposited amorphous InSnZnO thin films with different nitrogen/oxygen ratios carrier gases and their applications to thin-film transistors

Abstract

This study investigates InSnZnO thin films deposited using mist chemical vapor deposition with different nitrogen (N2)/oxygen (O2) ratios of carrier gases. The crystallinity and bandgap of InSnZnO are not affected by the carrier gases; however, the content of the oxygen deficiency of the InSnZnO thin films reduces when the N2/O2 mixed carrier gases have higher oxygen ratio. The InSnZnO thin-film transistor (TFT) shows the highest field-effect mobility (65.04 cm2V−1s−1) when N2 is used as the carrier gas to deposit the InSnZnO thin film. Although the field-effect mobility of the InSnZnO TFT that uses the N2 (60 vol%)/O2 (40 vol%) mixed carrier gas to deposit InSnZnO thin film is the lowest (47.65 cm2V−1s−1), it is still higher than those of the amorphous InGaZnO thin film transistors (∼10 cm2V−1s−1). Furthermore, the InSnZnO TFT using the N2 (60 vol%)/O2 (40 vol%) mixed carrier gas to deposit InSnZnO thin film exhibits the steepest subthreshold slope (102 mV/dec), the largest on/off current ratio (4.6 × 107), and the most stable electrical characteristics after the negative bias stress test for 10,800 s.