Effects of water and hydrogen introduction during In-Ga-Zn-O sputtering on the performance of low-temperature processed thin-film transistors

In-Ga-Zn-O (IGZO) films were deposited by sputtering in Ar + O-2 + H-2 and Ar + H2O atmosphere to investigate the effects of H-2 and H2O introduction on physical and electrical properties of IGZO films and thin-film transistors (TFTs). A substantial reduction and oxidation of the IGZO films were confirmed by introducing H-2 and H2O, respectively. We found that electron traps were formed for the Ar + H2O-sputtered IGZO TFTs, resulting in a degradation of field-effect mobility (mu(FE)), subthreshold swing (S.S.), and hysteresis (V-H). In contrast, such degradations were not observed in the Ar + O-2 + H-2-sputtered IGZO TFTs and it exhibited mu(FE) of 12.5 cm(2) V-1 s(-1), S.S. of 0.15 V dec(-1), and V-H of 0.5 V. Hard X-ray photoelectron spectroscopy analysis revealed that excess oxygen incorporated during Ar + H2O sputtering is a possible cause of the TFT degradation. Thus, the reduction process, namely, Ar + O-2 + H-2 sputtering, is a promising approach for low-temperature-processed (similar to 150 degrees C) oxide TFTs for future flexible device applications.

Automated summary

This study investigated the effects of introducing H-2 and H2O on IGZO films and TFTs deposited by sputtering in different atmospheres. Results showed that the introduction of H-2 and H2O led to degradation in performance of IGZO TFTs, while the reduction process of Ar + O-2 + H-2 sputtering showed promising results for future low-temperature-processed oxide TFTs.