Threshold voltage control of oxide nanowire transistors using nitrogen plasma treatment

In developing complementary metal-oxide semiconductor logic circuits using N-type semiconducting nanowires, threshold voltage (Vth) control is crucial because the driving voltage should be established in relation to the Vth dispersion of transistors. In this study, using N₂ plasma treatment, positive shifts of SnO₂ nanowire transistor (NWT) devices were produced as desired without degrading the nanowire surfaces. The NWT devices exhibited positive Vth shifts of ∼0.9 and ∼1.5 V and decreases in on-currents of ∼20% and ∼40% at plasma source powers of 200 and 400 W, respectively, without any changes in subthreshold slope or off-current. The positive Vth shifts and decreases in on-current can be explained by assuming that nitrogen ions (N3-) filled in for the existing oxygen vacancies (Vo, Vo+, and Vo ++) and that consequently, the amount of oxygen vacancies playing a role in electron-trapping decreased.