High-mobility InSnZnO Thin Film Transistors via Introducing Water Vapor Sputtering Gas

There is always a doubt that introducing water during oxide growing has a positive or negative effect on the properties of oxide films and devices. Herein, a comparison experiment on the condition of keeping the same oxygen atom flux in the sputtering chamber is designed to examine the influences of H2O on In–Sn–Zn–O (ITZO) films and their transistors. In comparison to no-water films, numerous unstable hydrogen-related defects are induced on with-water films at the as-deposited state. Paradoxically, this induction triggers an ordered enhancement in the microstructure of the films during conventional annealing, characterized by a reduction in H-related and vacancy (Vo) defects as well as an increase in film packing density and the M–O network ordering. Ultimately, the no-water thin-film transistors (TFTs) exhibit nonswitching behavior, whereas 5 sccm-water TFT demonstrates excellent electrical performance with a remarkable saturation field-effect mobility (μFE) of 122.10 ± 5.00 cm2·V–1·s–1, a low threshold (Vth) of −2.30 ± 0.40 V, a steep sub-threshold swing (SS) of 0.18 V·dec–1, a high output current (Ion) of 1420 μA, and a small threshold voltage shift ΔVth of −0.77 V in the negative bias stability test (3600 s).